Network Working Group J. Lyon Request for Comments: 2371 Microsoft Category: Standards Track K. Evans J. Klein Tandem Computers July 1998 Transaction Internet Protocol
Version 3.0
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited. Copyright Notice
Copyright (C) The Internet Society (1998). All Rights Reserved. Abstract
In many applications where different nodes cooperate on some work,
there is a need to guarantee that the work happens atomically. That
is, each node must reach the same conclusion as to whether the work
is to be completed, even in the face of failures. This document
proposes a simple, easily-implemented protocol for achieving this
end.
Table of Contents
1. Introduction 2
2. Example Usage 3
3. Transactions 4
4. Connections 4
5. Transaction Identifiers 5
6. Pushing vs. Pulling Transactions 5
7. TIP Transaction Manager Identification & Connection Establishment 6
8. TIP Uniform Resource Locators 8
9. States of a Connection 10
10. Protocol Versioning 12
11. Commands and Responses 12
12. Command Pipelining 13
13. TIP Commands 13
14. Error Handling 20 Lyon, et. al. Standards Track [Page 1]
15. Connection Failure and Recovery 20
16. Security Considerations 22
17. References 25
18. Authors’ Addresses 26
19. Comments 26 Appendix A. The TIP Multiplexing Protocol Version 2.0. 27 Fully Copyright Statement 31
1. Introduction
The standard method for achieving atomic commitment is the two-phase commit protocol; see [1] for an introduction to atomic commitment and two-phase commit protocols.
Numerous two-phase commit protocols have been implemented over the
years. However, none of them has become widely used in the Internet, due mainly to their complexity. Most of that complexity comes from
the fact that the two-phase commit protocol is bundled together with a specific program-to-program communication protocol, and that
protocol lives on top of a very large infrastructure.
This memo proposes a very simple two-phase commit protocol. It
achieves its simplicity by specifying only how different nodes agree on the outcome of a transaction; it allows (even requires) that the
subject matter on which the nodes are agreeing be communicated via
other protocols. By doing so, we avoid all of the issues related to
application communication semantics and data representation (to name just a few). Independent of the application communication protocol a transaction manager may use the Transport Layer Security protocol [3] to authenticate other transaction managers and encrypt messages.
It is envisioned that this protocol will be used mainly for a
transaction manager on one Internet node to communicate with a
transaction manager on another node. While it is possible to use this protocol for application programs and/or resource managers to speak
to transaction managers, this communication is usually intra-node,
and most transaction managers already have more-than-adequate
interfaces for the task.
While we do not expect this protocol to replace existing ones, we do expect that it will be relatively easy for many existing
heterogeneous transaction managers to implement this protocol for
communication with each other.
Further supplemental information regarding the TIP protocol can be
found in [5].
Lyon, et. al. Standards Track [Page 2]
2. Example Usage
Today the electronic shopping basket is a common metaphor at many
electronic store-fronts. Customers browse through an electronic
catalog, select goods and place them into an electronic shopping
basket. HTTP servers [2] provide various means ranging from URL
encoding to context cookies to keep track of client context (e.g.
the shopping basket of a customer) and resume it on subsequent
customer requests.
Once a customer has finished shopping they may decide to commit their selection and place the associated orders. Most orders may have no
relationship with each other except being executed as part of the
same shopping transaction; others may be dependent on each other (for example, if made as part of a special offering). Irrespective of
these details a customer will expect that all orders have been
successfully placed upon receipt of a positive acknowledgment.
Today’s electronic store-fronts must implement their own special
protocols to coordinate such placement of all orders. This
programming is especially complex when orders are placed through
multiple electronic store-fronts. This complexity limits the
potential utility of internet applications, and constrains growth.
The protocol described in this document intends to provide a standard for Internet servers to achieve agreement on a unit of shared work
(e.g. placement of orders in an electronic shopping basket). The
server (e.g. a CGI program) placing the orders may want to start a
transaction calling its local transaction manager, and ask other
servers participating in the work to join the transaction. The
server placing the orders passes a reference to the transaction as
user data on HTTP requests to the other servers. The other servers
call their transaction managers to start a local transaction and ask them to join the remote transaction using the protocol defined in
this document. Once all orders have been placed, execution of the
two-phase-commit protocol is delegated to the involved transaction
managers. If the transaction commits, all orders have been
successfully placed and the customer gets a positive acknowledgment. If the transaction aborts no orders will be placed and the customer
will be informed of the problem.
Transaction support greatly simplifies programming of these
applications as exception handling and failure recovery are delegated to a special component. End users are also not left having to deal
with the consequences of only partial success. While this example
shows how the protocol can be used by HTTP servers, applications may use the protocol when accessing a remote database (e.g. via ODBC), or invoking remote services using other already existing protocols (e.g. Lyon, et. al. Standards Track [Page 3]
RPC). The protocol makes it easy for applications in a heterogeneous network to participate in the same transaction, even if using
different communication protocols.
3. Transactions
"Transaction" is the term given to the programming model whereby
computational work performed has atomic semantics. That is, either
all work completes successfully and changes are made permanent (the
transaction commits), or if any work is unsuccessful, changes are
undone (the transaction aborts). The work comprising a transaction
(unit of work), is defined by the application.
4. Connections
The Transaction Internet Protocol (TIP) requires a reliable ordered
stream transport with low connection setup costs. In an Internet (IP) environment, TIP operates over TCP, optionally using TLS to provide a secured and authenticated connection, and optionally using a protocol to multiplex light-weight connections over the same TCP or TLS
connection.
Transaction managers that share transactions establish a TCP (and
optionally a TLS) connection. The protocol uses a different
connection for each simultaneous transaction shared betwween two
transaction managers. After a transaction has ended, the connection
can be reused for a different transaction.
Optionally, instead of associating a TCP or TLS connection with only a single transaction, two transaction managers may agree on a
protocol to multiplex light-weight connections over the same TCP or
TLS connection, and associate each simultaneous transaction with a
separate light-weight connection. Using light-weight connections
reduces latency and resource consumption associated with executing
simultaneous transactions. Similar techniques as described here are
widely used by existing transaction processing systems. See Appendix A for an example of one such protocol.
Note that although the TIP protocol itself is described only in terms of TCP and TLS, there is nothing to preclude the use of TIP with
other transport protocols. However, it is up to the implementor to
ensure the chosen transport provides equivalent semantics to TCP, and to map the TIP protocol appropriately.
Lyon, et. al. Standards Track [Page 4]
In this document the terms "connection" or "TCP connection" can refer to a TIP TCP connection, a TIP TLS connection, or a TIP multiplexing connection (over either TCP or TLS). It makes no difference which,
the behavior is the same in each case. Where there are differences in behavior between the connection types, these are stated explicitly. 5. Transaction Identifiers
Unfortunately, there is no single globally-accepted standard for the format of a transaction identifier; there are various standard and
proprietary formats. Allowed formats for a TIP transaction
identifier are described below in the section "TIP Uniform Resource
Locators". A transaction manager may map its internal transaction
identifiers into this TIP format in any manner it sees fit.
Furthermore, each party in a superior/subordinate relationship gets
to assign its own identifier to the transaction; these identifiers
are exchanged when the relationship is first established. Thus, a
transaction manager gets to use its own format of transaction
identifier internally, but it must remember a foreign transaction
identifier for each superior/subordinate relationship in which it is involved.
6. Pushing vs. Pulling Transactions
Suppose that some program on node "A" has created a transaction, and wants some program on node "B" to do some work as part of the
transaction. There are two classical ways that he does this,
referred to as the "push" model and the "pull" model.
In the "push" model, the program on A first asks his transaction
manager to export the transaction to node B. A’s transaction manager sends a message to B’s TM asking it to instantiate the transaction as a subordinate of A, and return its name for the transaction. The
program on A then sends a message to its counterpart on B on the
order of "Do some work, and make it part of the transaction that your transaction manager already knows of by the name ...". Because A’s
TM knows that it sent the transaction to B’s TM, A’s TM knows to
involve B’s TM in the two-phase commit process.
In the "pull" model, the program on A merely sends a message to B on the order of "Do some work, and make it part of the transaction that my TM knows by the name ...". The program on B asks its TM to enlist in the transaction. At that time, B’s TM will "pull" the transaction over from A. As a result of this pull, A’s TM knows to involve B’s
TM in the two-phase commit process.
The protocol described here supports both the "push" and "pull"
models.
Lyon, et. al. Standards Track [Page 5]
7. TIP Transaction Manager Identification and Connection Establishment
In order for TIP transaction managers to connect they must be able to identify and locate each other. The information necessary to do this is described by the TIP transaction manager address.
[This specification does not prescribe how TIP transaction managers
initially obtain the transaction manager address (which will probably be via some implementation-specific configuration mechanism).]
TIP transaction manager addresses take the form:
The
where
used.
A
service. It must be sufficiently qualified to be useful to the
receiver of the command.
An
numbers separated by period characters.
The
component.
The
defined by
The
"/" [path_segments]
path_segments = segment *( "/" segment )
segment = *pchar *( ";" param )
param = *pchar
pchar = unreserved | escaped | ":" | "@" | "&" | "=" | "+"
unreserved = ASCII character octets with values in the range
Lyon, et. al. Standards Track [Page 6]
(inclusive): 48-57, 65-90, 97-122 | "$" | "-" | "_" | "." | "!" | "?" | "*" | "’" | "(" | ")" | ","
escaped = "%" hex hex
hex = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" |
"A" | "B" | "C" | "D" | "E" | "F" | "a" | "b" | "c" | "d" |
"e" | "f"
The
separated by a single slash "/" character. Within a path segment, the characters "/", ";", "=", and "?" are reserved. Each path segment may include a sequence of parameters, indicated by the semicolon ";"
character. The parameters are not significant to the parsing of
relative references.
[It is intended that the form of the transaction manager address
follow the proposed scheme for Uniform Resource Identifiers (URI)
[8].]
The TIP transaction manager address therefore provides to the
connection initiator (the primary) the endpoint identifier to be used for the TCP connection (
(the secondary) the path to be used to locate the specific TIP
transaction manager (
for the connection between the primary and secondary TIP transaction managers to be established.
After a connection has been established, the primary party issues an IDENTIFY command. This command includes as parameters two transaction manager addresses: the primary transaction manager address, and the
secondary transaction manager address.
The primary transaction manager address identifies the TIP
transaction manager that initiated the connection. This information
is required in certain cases after connection failures, when one of
the parties of the connection must re-establish a new connection to
the other party in order to complete the two-phase-commit protocol.
If the primary party needs to re-establish the connection, the job is easy: a connection is established in the same way as was the original connection. However, if the secondary party needs to re-establish the connection, it must be known how to contact the initiator of the
original connection. This information is supplied to the secondary
via the primary transaction manager address on the IDENTIFY command. If a primary transaction manager address is not supplied, the primary party must not perform any action which would require a connection to be re-established (e.g. to perform recovery actions).
Lyon, et. al. Standards Track [Page 7]
The secondary transaction manager address identifies the receiving
TIP transaction manager. In the case of TIP communication via
intermediate proxy servers, this URL may be used by the proxy servers to correctly identify and connect to the required TIP transaction
manager.
8. TIP Uniform Resource Locators
Transactions and transaction managers are resources associated with
the TIP protocol. Transaction managers and transactions are located
using the transaction manager address scheme. Once a connection has
been established, TIP commands may be sent to operate on transactions associated with the respective transaction managers.
Applications which want to pull a transaction from a remote node must supply a reference to the remote transaction which allows the local
transaction manager (i.e. the transaction manager pulling the
transaction) to connect to the remote transaction manager and
identify the particular transaction. Applications which want to push a transaction to a remote node must supply a reference to the remote transaction manager (i.e. the transaction manager to which the
transaction is to be pushed), which allows the local transaction
manager to locate the remote transaction manager. The TIP protocol
defines a URL scheme [4] which allows applications and transaction
managers to exchange references to transaction managers and
transactions.
A TIP URL takes the form:
tip://
where
manager (as defined in Section 7 above); and
specifies a transaction identifier, which may take one of two forms
(standard or non-standard):
i. "urn:"
A standard transaction identifier, conforming to the proposed
Internet Standard for Uniform Resource Names (URNs), as specified
by RFC2141; where
the Namespace Specific String. The Namespace ID determines the
syntactic interpretation of the Namespace Specific String. The
Namespace Specific String is a sequence of characters representing a transaction identifier (as defined by
contents of these fields are specified by [6] (valid characters,
encoding, etc.).
Lyon, et. al. Standards Track [Page 8]
This format of
transaction identifiers in terms of standard representations.
Examples for
tip://123.123.123.123/?urn:xopen:xid
Note that Namespace Ids require registration. See [7] for details
on how to do this.
ii.
A sequence of printable ASCII characters (octets with values in the range 32 through 126 inclusive (excluding ":") representing a
transaction identifier. In this non-standard case, it is the
combination of identifier> which ensures global uniqueness. e.g. tip://123.123.123.123/?transid1 To create a non-standard TIP URL from a transaction identifier, first replace any reserved characters in the transaction identifier with their equivalent escape sequences, then insert the appropriate transaction manager address. If the transaction identifier is one that you created, insert your own transaction manager address. If the transaction identifier is one that you received on a TIP connection that you initiated, use the secondary transaction manager address that was sent in the IDENTIFY command. If the transaction identifier is one that you received on a TIP connection that you did not initiate, use the primary transaction manager address that was received in the IDENTIFY command. TIP URLs must be guaranteed globally unique for all time. This uniqueness constraint ensures TIP URLs are never duplicated, thereby preventing possible non-deterministic behaviour. How uniqueness is achieved is implementation specific. For example, the Universally Unique Identifier (UUID, also known as a Globally Unique Identifier, or GUID (see [9])) could be used as part of the Except as otherwise described above, the TIP URL scheme follows the rules for reserved characters as defined in [4], and uses escape sequences as defined in [4] Section 5. Note that the TIP protocol itself does not use the TIP URL scheme (it does use the transaction manager address scheme). The TIP URL scheme is proposed as a standard way to pass transaction identification Lyon, et. al. Standards Track [Page 9] information through other protocols. e.g. between cooperating application processes. The TIP URL may then be used to communicate to the local transaction manager the information necessary to associate the application with a particular TIP transaction. e.g. to PULL the transaction from a remote transaction manager. It is anticipated that each TIP implementation will provide some set of APIs for this purpose ([5] includes examples of such APIs). 9. States of a Connection At any instant, only one party on a connection is allowed to send commands, while the other party is only allowed to respond to commands that he receives. Throughout this document, the party that is allowed to send commands is called "primary"; the other party is called "secondary". Initially, the party that initiated the connection is primary; however, a few commands cause the roles to switch. A connection returns to its original polarity whenever the Idle state is reached. When multiplexing is being used, these rules apply independently to each "virtual" connection, regardless of the polarity of the underlying connection (which will be in the Multiplexing state). Note that commands may be sent "out of band" by the secondary via the use of pipelining. This does not affect the polarity of the connection (i.e. the roles of primary and secondary do not switch). See section 12 for details. In the normal case, TIP connections should only be closed by the primary, when in Initial state. It is generally undesirable for a connection to be closed by the secondary, although this may be necessary in certain error cases. At any instant, a connection is in one of the following states. From the point of view of the secondary party, the state changes when he sends a reply; from the point of view of the primary party, the state changes when he receives a reply. Initial: The initial connection starts out in the Initial state. Upon entry into this state, the party that initiated the connection becomes primary, and the other party becomes secondary. There is no transaction associated with the connection in this state. From this state, the primary can send an IDENTIFY or a TLS command. Idle: In this state, the primary and the secondary have agreed on a protocol version, and the primary supplied an identifier to the secondary party to reconnect after a failure. There is no transaction associated with the connection in this state. Upon Lyon, et. al. Standards Track [Page 10] entry to this state, the party that initiated the connection becomes primary, and the other party becomes secondary. From this state, the primary can send any of the following commands: BEGIN, MULTIPLEX, PUSH, PULL, QUERY and RECONNECT. Begun: In this state, a connection is associated with an active transaction, which can only be completed by a one-phase protocol. A BEGUN response to a BEGIN command places a connection into this state. Failure of a connection in Begun state implies that the transaction will be aborted. From this state, the primary can send an ABORT, or COMMIT command. Enlisted: In this state, the connection is associated with an active transaction, which can be completed by a one-phase or, two-phase protocol. A PUSHED response to a PUSH command, or a PULLED response to a PULL command, places the connection into this state. Failure of the connection in Enlisted state implies that the transaction will be aborted. From this state, the primary can send an ABORT, COMMIT, or PREPARE command. Prepared: In this state, a connection is associated with a transaction that has been prepared. A PREPARED response to a PREPARE command, or a RECONNECTED response to a RECONNECT command places a connection into this state. Unlike other states, failure of a connection in this state does not cause the transaction to automatically abort. From this state, the primary can send an ABORT, or COMMIT command. Multiplexing: In this state, the connection is being used by a multiplexing protocol, which provides its own set of connections. In this state, no TIP commands are possible on the connection. (Of course, TIP commands are possible on the connections supplied by the multiplexing protocol.) The connection can never leave this state. Tls: In this state, the connection is being used by the TLS protocol, which provides its own secured connection. In this state, no TIP commands are possible on the connection. (Of course, TIP commands are possible on the connection supplied by the TLS protocol.) The connection can never leave this state. Error: In this state, a protocol error has occurred, and the connection is no longer useful. The connection can never leave this state. Lyon, et. al. Standards Track [Page 11] 10. Protocol Versioning This document describes version 3 of the protocol. In order to accommodate future versions, the primary party sends a message indicating the lowest and the highest version number it understands. The secondary responds with the highest version number it understands. After such an exchange, communication can occur using the smaller of the highest version numbers (i.e., the highest version number that both understand). This exchange is mandatory and occurs using the IDENTIFY command (and IDENTIFIED response). If the highest version supported by one party is considered obsolete and no longer supported by the other party, no useful communication can occur. In this case, the newer party should merely drop the connection. 11. Commands and Responses All commands and responses consist of one line of ASCII text, using only octets with values in the range 32 through 126 inclusive, followed by either a CR (an octet with value 13) or an LR (an octet with value 10). Each line can be split up into one or more "words", where successive words are separated by one or more space octets (value 32). Arbitrary numbers of spaces at the beginning and/or end of each line are allowed, and ignored. Lines that are empty, or consist entirely of spaces are ignored. (One implication of this is that you can terminate lines with both a CR and an LF if desired; the LF will be treated as terminating an empty line, and ignored.) In all cases, the first word of each line indicates the type of command or response; all defined commands and responses consist of upper-case letters only. For some commands and responses, subsequent words convey parameters for the command or response; each command and response takes a fixed number of parameters. All words on a command or response line after (and including) the first undefined word are totally ignored. These can be used to pass human-readable information for debugging or other purposes. Lyon, et. al. Standards Track [Page 12] 12. Command Pipelining In order to reduce communication latency and improve efficiency, it is possible for multiple TIP "lines" (commands or responses) to be pipelined (concatenated) together and sent as a single message. Lines may also be sent "ahead" (by the secondary, for later procesing by the primary). Examples are an ABORT command immediately followed by a BEGIN command, or a COMMITTED response immediately followed by a PULL command. The sending of pipelined lines is an implementation option. Likewise which lines are pipelined together. Generally, it must be certain that the pipelined line will be valid for the state of the connection at the time it is processed by the receiver. It is the responsibility of the sender to determine this. All implementations must support the receipt of pipelined lines - the rules for processing of which are described by the following paragraph: When the connection state is such that a line should be read (either command or response), then that line (when received) is processed. No more lines are read from the connection until processing again reaches such a state. If a line is received on a connection when it is not the turn of the other party to send, that line is _not_ rejected. Instead, the line is held and processed when the connection state again requires it. The receiving party must process lines and issue responses in the order of lines received. If a line causes an error the connection enters the Error state, and all subsequent lines on the connection are discarded. 13. TIP Commands Commands pertain either to connections or transactions. Commands which pertain to connections are: IDENTIFY, MULTIPLEX and TLS. Commands which pertain to transactions are: ABORT, BEGIN, COMMIT, PREPARE, PULL, PUSH, QUERY, and RECONNECT. Following is a list of all valid commands, and all possible responses to each: ABORT This command is valid in the Begun, Enlisted, and Prepared states. It informs the secondary that the current transaction of the connection will abort. Possible responses are: Lyon, et. al. Standards Track [Page 13] The transaction has aborted; the connection enters Idle state. ERROR The command was issued in the wrong state, or was malformed. The connection enters the Error state. BEGIN This command is valid only in the Idle state. It asks the secondary to create a new transaction and associate it with the connection. The newly created transaction will be completed with a one-phase protocol. Possible responses are: BEGUN A new transaction has been successfully begun, and that transaction is now the current transaction of the connection. The connection enters Begun state. NOTBEGUN A new transaction could not be begun; the connection remains in Idle state. ERROR The command was issued in the wrong state, or was malformed. The connection enters the Error state. COMMIT This command is valid in the Begun, Enlisted or Prepared states. In the Begun or Enlisted state, it asks the secondary to attempt to commit the transaction; in the Prepared state, it informs the secondary that the transaction has committed. Note that in the Enlisted state this command represents a one-phase protocol, and should only be done when the sender has 1) no local recoverable resources involved in the transaction, and 2) only one subordinate (the sender will not be involved in any transaction recovery process). Possible responses are: ABORTED This response is possible only from the Begun and Enlisted states. It indicates that some party has vetoed the commitment of the transaction, so it has been aborted instead of committing. The connection enters the Idle state. Lyon, et. al. Standards Track [Page 14] This response indicates that the transaction has been committed, and that the primary no longer has any responsibilities to the secondary with respect to the transaction. The connection enters the Idle state. ERROR The command was issued in the wrong state, or was malformed. The connection enters the Error state. ERROR This command is valid in any state; it informs the secondary that a previous response was not recognized or was badly formed. A secondary should not respond to this command. The connection enters Error state. IDENTIFY This command is valid only in the Initial state. The primary party informs the secondary party of: 1) the lowest and highest protocol version supported (all versions between the lowest and highest must be supported; 2) optionally, an identifier for the primary party at which the secondary party can re-establish a connection if ever needed (the primary transaction manager address); and 3) an identifier which may be used by intermediate proxy servers to connect to the required TIP transaction manager (the secondary transaction manager address). If a primary transaction manager address is not supplied, the secondary party will respond with ABORTED or READONLY to any PREPARE commands. Possible responses are: IDENTIFIED The secondary party has been successfully contacted and has saved the primary transaction manager address. The response contains the highest protocol version supported by the secondary party. All future communication is assumed to take place using the smaller of the protocol versions in the IDENTIFY command and the IDENTIFIED response. The connection enters the Idle state. NEEDTLS The secondary party is only willing to communicate over TLS secured connections. The connection enters the Tls state, and all subsequent communication is as defined by the TLS protocol. This protocol will begin with the first octet after the line Lyon, et. al. Standards Track [Page 15] terminator of the IDENTIFY command (for data sent by the primary party), and the first byte after the line terminator of the NEEDTLS response (for data sent by the secondary party). This implies that an implementation must not send both a CR and a LF octet after either the IDENTIFY command or the NEEDTLS response, lest the LF octet be mistaken for the first byte of the TLS protocol. The connection provided by the TLS protocol starts out in the Initial state. After TLS has been negotiated, the primary party must resend the IDENTIFY command. If the primary party cannot support (or refuses to use) the TLS protocol, it closes the connection. ERROR The command was issued in the wrong state, or was malformed. This response also occurs if the secondary party does not support any version of the protocol in the range supported by the primary party. The connection enters the Error state. The primary party should close the connection. MULTIPLEX This command is only valid in the Idle state. The command seeks agreement to use the connection for a multiplexing protocol that will supply a large number of connections on the existing connection. The primary suggests a particular multiplexing protocol. The secondary party can either accept or reject use of this protocol. At the present, the only defined protocol identifier is "TMP2.0", which refers to the TIP Multiplexing Protocol, version 2.0. See Appendix A for details of this protocol. Other protocol identifiers may be defined in the future. If the MULTIPLEX command is accepted, the specified multiplexing protocol will totally control the underlying connection. This protocol will begin with the first octet after the line terminator of the MULTIPLEX command (for data sent by the initiator), and the first byte after the line terminator of the MULTIPLEXING response (for data received by the initiator). This implies that an implementation must not send both a CR and a LF octet after either the MULTIPLEX command or the MULTIPLEXING response, lest the LF octet be mistaken for the first byte of the multiplexing protocol. Note that when using TMP V2.0, a single TIP command (TMP application message) must be wholly contained within a single TMP packet (the TMP PUSH flag is not used by TIP). Possible responses to the MULTIPLEX command are: Lyon, et. al. Standards Track [Page 16] MULTIPLEXING The secondary party agrees to use the specified multiplexing protocol. The connection enters the Multiplexing state, and all subsequent communication is as defined by that protocol. All connections created by the multiplexing protocol start out in the Idle state. CANTMULTIPLEX The secondary party cannot support (or refuses to use) the specified multiplexing protocol. The connection remains in the Idle state. ERROR The command was issued in the wrong state, or was malformed. The connection enters the Error state. PREPARE This command is valid only in the Enlisted state; it requests the secondary to prepare the transaction for commitment (phase one of two-phase commit). Possible responses are: PREPARED The subordinate has prepared the transaction; the connection enters PREPARED state. ABORTED The subordinate has vetoed committing the transaction. The connection enters the Idle state. After this response, the superior has no responsibilities to the subordinate with respect to the transaction. READONLY The subordinate no longer cares whether the transaction commits or aborts. The connection enters the Idle state. After this response, the superior has no responsibilities to the subordinate with respect to the transaction. ERROR The command was issued in the wrong state, or was malformed. The connection enters the Error state. PULL This command is only valid in Idle state. This command seeks to establish a superior/subordinate relationship in a transaction, with the primary party of the connection as the subordinate (i.e., Lyon, et. al. Standards Track [Page 17] he is pulling a transaction from the secondary party). Note that the entire value of transaction identifier. Possible responses are: PULLED The relationship has been established. Upon receipt of this response, the specified transaction becomes the current transaction of the connection, and the connection enters Enlisted state. Additionally, the roles of primary and secondary become reversed. (That is, the superior becomes the primary for the connection.) NOTPULLED The relationship has not been established (possibly, because the secondary party no longer has the requested transaction). The connection remains in Idle state. ERROR The command was issued in the wrong state, or was malformed. The connection enters the Error state. PUSH This command is valid only in the Idle state. It seeks to establish a superior/subordinate relationship in a transaction with the primary as the superior. Note that the entire value of PUSHED The relationship has been established, and the identifier by which the subordinate knows the transaction is returned. The transaction becomes the current transaction for the connection, and the connection enters Enlisted state. ALREADYPUSHED The relationship has been established, and the identifier by which the subordinate knows the transaction is returned. However, the subordinate already knows about the transaction, and is expecting the two-phase commit protocol to arrive via a different connection. In this case, the connection remains in the Idle state. NOTPUSHED The relationship could not be established. The connection remains in the Idle state. Lyon, et. al. Standards Track [Page 18] ERROR The command was issued in the wrong state, or was malformed. The connection enters Error state. QUERY This command is valid only in the Idle state. A subordinate uses this command to determine whether a specific transaction still exists at the superior. Possible responses are: QUERIEDEXISTS The transaction still exists. The connection remains in the Idle state. QUERIEDNOTFOUND The transaction no longer exists. The connection remains in the Idle state. ERROR The command was issued in the wrong state, or was malformed. The connection enters Error state. RECONNECT This command is valid only in the Idle state. A superior uses the command to re-establish a connection for a transaction, when the previous connection was lost during Prepared state. Possible responses are: RECONNECTED The subordinate accepts the reconnection. The connection enters Prepared state. NOTRECONNECTED The subordinate no longer knows about the transaction. The connection remains in Idle state. ERROR The command was issued in the wrong state, or was malformed. The connection enters Error state. TLS This command is valid only in the Initial state. A primary uses this command to attempt to establish a secured connection using TLS. Lyon, et. al. Standards Track [Page 19] If the TLS command is accepted, the TLS protocol will totally control the underlying connection. This protocol will begin with the first octet after the line terminator of the TLS command (for data sent by the primary), and the first byte after the line terminator of the TLSING response (for data received by the primary). This implies that an implementation must not send both a CR and a LF octet after either the TLS command or the TLSING response, lest the LF octet be mistaken for the first byte of the TLS protocol. Possible responses to the TLS command are: TLSING The secondary party agrees to use the TLS protocol [3]. The connection enters the Tls state, and all subsequent communication is as defined by the TLS protocol. The connection provided by the TLS protocol starts out in the Initial state. CANTTLS The secondary party cannot support (or refuses to use) the TLS protocol. The connection remains in the Initial state. ERROR The command was issued in the wrong state, or was malformed. The connection enters the Error state. 14. Error Handling If either party receives a line that it cannot understand it closes the connection. If either party (either a command or a response), receives an ERROR indication or an ERROR response on a connection the connection enters the Error state and no further communication is possible on that connection. An implementation may decide to close the connection. Closing of the connection is treated by the other party as a communication failure. Receipt of an ERROR indication or an ERROR response indicates that the other party believes that you have not properly implemented the protocol. 15. Connection Failure and Recovery A connection failure may be caused by a communication failure, or by any party closing the connection. It is assumed TIP implementations will use some private mechanism to detect TIP connection failure (e.g. socket keepalive, or a timeout scheme). Lyon, et. al. Standards Track [Page 20] 6-01 因特网的域名结构是怎么样的？它与目前的电话网的号码结构有何异同之处？ 答： （1）域名的结构由标号序列组成，各标号之间用点隔开： … . 三级域名. 二级域名. 顶级域名 各标号分别代表不同级别的域名。 （2）电话号码分为国家号结构分为（中国+86）、区号、本机号。 6-02 域名系统的主要功能是什么？域名系统中的本地域名服务器、根域名服务器、顶级域名服务器以及权限域名权服务器有何区别？ 答: 域名系统的主要功能：将域名解析为主机能识别的IP地址。 因特网上的域名服务器系统也是按照域名的层次来安排的。每一个域名服务器都只对域名体系中的一部分进行管辖。共有三种不同类型的域名服务器。即本地域名服务器、根域名服务器、授权域名服务器。当一个本地域名服务器不能立即回答某个主机的查询时，该本地域名服务器就以DNS客户的身份向某一个根域名服务器查询。若根域名服务器有被查询主机的信息，就发送DNS回答报文给本地域名服务器，然后本地域名服务器再回答发起查询的主机。但当根域名服务器没有被查询的主机的信息时，它一定知道某个保存有被查询的主机名字映射的授权域名服务器的IP地址。通常根域名服务器用来管辖顶级域。根域名服务器并不直接对顶级域下面所属的所有的域名进行转换，但它一定能够找到下面的所有二级域名的域名服务器。每一个主机都必须在授权域名服务器处注册登记。通常，一个主机的授权域名服务器就是它的主机ISP的一个域名服务器。授权域名服务器总是能够将其管辖的主机名转换为该主机的IP地址。 因特网允许各个单位根据本单位的具体情况将本域名划分为若干个域名服务器管辖区。一般就在各管辖区中设置相应的授权域名服务器。 6-03 举例说明域名转换的过程。域名服务器中的高速缓存的作用是什么？ 答： （1）把不方便记忆的IP地址转换为方便记忆的域名地址。 （2）作用：可大大减轻根域名服务器的负荷，使因特网上的DNS 查询请求和回答报文的数量大为减少。 6-04 设想有一天整个因特网的DNS系统都瘫痪了（这种情况不大会出现），试问还可以给朋友发送电子邮件吗？ 答：不能； 6-05 文件传送协议FTP的主要工作过程是怎样的？为什么说FTP是带外传送控制信息？主进程和从属进程各起什么作用？ 答： （1）FTP使用客户服务器方式。一个FTP服务器进程可同时为多个客户进程提供服务。FTP 的服务器进程由两大部分组成：一个主进程，负责接受新的请求；另外有若干个从属进程，负责处理单个请求。 主进程的工作步骤： 1、打开熟知端口（端口号为21），使客户进程能够连接上。 2、等待客户进程发出连接请求。 1．局域网、城域网、广域网 2．专用网、公用网 3．WWW、FTP、EMAIL 4．计算机网络系统 5．报文交换、报文分组交换 6．电路交换 7．防火墙 8．telnet 9．TCP/IP协议 10．域名 二、选择题 1-5：ABDDB 6-10：ABDAD 三、判断 1-5：TTFFF 6-10：FTFFF 四、简答题 1．解： （1）把分布在不同地理位置上的具有独立功能的多台计算机、终端及其附属设备在物理上互连，按照网络协议相互通信，以共享硬件、软件和数据资源为目标的系统称作计算机网络。 （2）主要功能：数据通信、资源共享、计算机系统可靠性和可用性的提高、易于进行分布处理 2．解：按使用范围分为局域网、城域网和广域网 按建设计算机网络的属性来分：公用网和专用网。 按网络的拓扑结构来分：星形、总线形、环形、树形、全互连形和不规则形。 按信息的交换方式来分：电路交换、报文交换和报文分组交换。 3．（1）远程登录服务Telnet（Remote Login） （2）文件传送服务FTP （3）电子邮件服务E-mail（Electronic Mail） （4）电子公告板系统（BBS） （5）万维网 4．解：在对等网络模式中，相连的机器之间彼此处于同等地位，没有主从之分故又称为对等网络（Peer to Peer network）。它们能够相互共享资源，每台计算机都能以同样方式作用于对方。5． （1）星型拓扑结构是由中心结点和通过点对点链路连接到中心结点的各站点组成。星型拓扑结构的中心结点是主结点，它接收各分散站点的信息再转发给相应的站点。目前这种星型拓扑结构几乎是Ethernet双绞线网络专用的。这种星型拓扑结构的中心结点是由集线器或者是交换机来承担的。 （2）星型拓扑结构有以下优点：由于每个设备都用一根线路和中心结点相连，如果这根线路损坏，或与之相连的工作站出现故障时，在星型拓扑结构中，不会对整个网络造成大的影响，而仅会影响该工作站；网络的扩展容易；控制和诊断方便；访问协议简单。 星型拓扑结构也存在着一定的缺点： 一、选择题 题目1 计算机网络的功能有（）。 选择一项： A. 用户管理 B. 病毒管理 C. 资源共享正确 D. 站点管理 题目分析： 计算机网络的功能有：（1）资源共享；（2）数据通信；（3）集中管理；（4）增加可靠性；（5）提高系统的处理能力和安全功能。其中，资源共享和数据通信是计算机网络最基本的两大功能。 正确答案是：资源共享 题目2 网络资源子网负责（）。 选择一项： A. 信息处理 B. 数据通信 C. 数字认证机制 D. 路由 题目分析： “资源子网”主要负责：（1）全网的信息处理；（2）为网络用户提供网络服务；（3）资源共享功能。 正确答案是：信息处理 题目3 通常按网络覆盖的地理范围分类，可分为局域网、（）和广域网三种。 选择一项： A. 星型网络 B. 有线网 C. 城域网 D. 无线网 反馈 Your answer is incorrect. 题目分析： 计算机网络按网络覆盖的地理范围进行分类可以分为：（1）局域网；（2）城域网；（3）广域网。 正确答案是：城域网 题目4 为了简化计算机网络的分析与设计，有利于网络的硬件和软件配置，按照计算机网络的系统功能，一个计算机网络中实现网络通信功能的设备及其软件的集合称为网络的（）。 选择一项： A. 无线网 B. 通信子网 C. 有线网 D. 资源子网 反馈 Your answer is incorrect. 题目分析： 计算机网络系统是由通信子网和资源子网组成。通信子网：一个计算机网络中实现网络通信功能的设备及其软件的集合。资源子网：网络中实现资源共享功能的设备及其软件的集合。 第4章计算机网络与因特网 4.1 计算机网络基础 计算机网络的组成与分类 ●计算机网络：利用通信设备和网络软件，把地理位置分散且功能独立的多台计算机（或 其它智能设备）以相互共享资源和进行信息传递为目的连接起来的一个系统。 ●计算机网络的特性：与电话、电视系统不同，计算机网络是一种数据通信系统，传输的 都是二进制形式的数据 ●通信协议：为确保网络的计算机能正确交换数据，它们必须遵循的一组共同的规则和约 定，这些规则、规定或标准称为通信协议，简称为协议。 ●计算机组网的目的 数据通信：使计算机之间可以相互传送数据，方便地交换信息 资源共享：用户可以共享网络中其他计算机的软件、硬件和数据资源 实现分布式信息处理：大型问题可以借助于分散在网络中的多台计算机协同完成； 分散在各地各部门的用户通过网络合作完成一项共同的任务提高计算机系统的可靠性和可用性：计算机出现故障时，网络中的计算机可以互 为后备；计算机负荷过重时，可将部分任务分配给空闲的计算机 ●计算机网络的分类 ?按使用的传输介质可分为：有线网；无线网 ?按网络的使用性质可分为：公用网；专用网；虚拟专网(VPN) ?按网络的使用对象可以分为：企业网；政府网；金融网；校园网等 ?按网络所覆盖的地域范围可以分为： 局域网(LAN)：使用专用通信线路把较小地域范围（一幢楼房、一个楼群、一 个单位或一个小区）中的计算机连接而成的网络 广域网(WAN) ：把相距遥远的许多局域网和计算机用户互相连接在一起的网 络，作用范围通常从几十km到几千km，广域网有时也称为 远程网 城域网(MAN) ：作用范围在广域网和局域网之间，其作用距离约为5km～50 km，例如一个城市范围的计算机网络 网络工作模式和网络服务 ●从共享资源的角度看，网络中的计算机可以是： 客户机：使用其它计算机资源的计算机 服务器：提供共享资源（如数据文件、磁盘空间、打印机、处理器等）给其它计算机使用的计算机 每一台联网的计算机，其“身份”或者是客户机，或者是服务器，或者两种身份兼而有之●计算机网络有两种基本的工作模式： 对等模式（peer-to-peer，简称P2P）：网络中每台计算机既可以作为客户机也可以 项目六计算机网络基础与Internet应用 任务一认识网络 v【任务分析】 v计算机网络是计算机技术和通信技术相结合的产物，是计算机应用的一个重要领域，它实现了资源共享，人们可以在办公室、家里或其它任何地方，访问、查询网上的任何资源，极大的提高了工作效率，促进了办公自动化、工厂自动化、家庭自动化的发展，给人类带来了巨大便利。v本任务内容包括：计算机网络的形成与发展，计算机连网的作用，计算机网络定义，计算机网络的分类，计算机网络的组成与结构，计算机网络的拓扑结构等，让大家能够认识与掌握网络的基本内涵。 v【基础知识】 一、计算机网络的定义 从计算机与通信技术结合的广义出发，把计算机网络定义为：“计算机技术与通信技术结合，实现远程信息处理或达到资源共享的系统”。按照这个定义，20世界50年代的“终端——计算机网”，20世纪60年代的“计算机——计算机网”，以及目前正在发展的“分布 式计算机网”均属计算机网络。 从物理结构上看，又把计算机网络定义为：“在协议的控制下，由若干计算机、终端设备、数据传输设备的通信系统控制处理机等组成的系统集合”。这一定义强调了计算机网络是在协议控制下实现计算机之间互连的。 在计算机网络发展过程的不同阶段中，人们对计算机网络提出了不同的定义。不同的定 义反映着当时网络技术发展的水平，以及人们对网络的认识程度。那么，什么是计算机 网络？ 随着近年来计算机网络技术的不断发展和完善，对计算机网络的描述也更加全面：计算 机网络就是利用通信线路和设备，将分散在不同地点、并具有独立功能的多个计算机系 统互连起来，按照网络协议，在功能完善的网络软件支持下，实现资源共享和信息交换 的系统。 计算机网络期末考试试卷及答案 1、网络协议的三个要素为（语法）、（语义）和（同步）。 2、TCP/IP 体系的电子邮件系统规定电子邮件地址的格式为（收件人邮箱名@邮箱所在主机的域名）。 3、数据链路层解决的三个基本问题是（封装成帧）、（透明传输）和（差错检测）。 4、用于在主机IP地址与MAC地址进行解析的协议称为（地址解析协议ARP ）协议。 5、自治系统内部使用最多的路由协议是（RIP）和（OSPF 协议）。BGP协议外部 6、已知IP地址是141.14.72.26，子网掩码是255.255.192.0，其网络地址为（ 141.14.64.0 ）。 7、传输层是为应用进程之间提供（端到端的逻辑通信），主要包括面向连接的（ TCP ）和无连接的（UDP ）两个协议。 8、负责将域名翻译成IP地址的系统叫做（）。 一、选择题（每题2分，共计30分） 1、广域网覆盖的地理范围从几十公里到几千公里。它的通信子网主要使用 （ B ） A、报文交换技术 B、分组交换技术 C、文件交换技术 D、电路交换技术 2、数据链路层中的数据块常被称为（ C ） A、信息 B、分组 C、帧 D、比特流 3、关于TCP/IP的IP层协议描述不正确的是（ D ） A、是点到点的协议 B、不能保证IP报文的可靠传送 C、是无连接的数据报传输机制 D、每一个IP数据包都需要对方应答 4、以下哪项不是IP路由器应具备的主要功能（C ） A、转发所收到的IP数据报 B、为需要转发的IP数据报选择最佳路径 C、分析IP数据报所携带的TCP内容 D、维护路由表信息 5、用集线器连接的工作站集合（ A ） A、同属一个冲突域，也同属一个广播域 B、不属一个冲突域，但同属一个广播域 C、不属一个冲突域，也不属一个广播域 D、同属一个冲突域，但不属一个广播域 6、标准TCP不支持的功能是（ D ）。 A、可靠数据传输 B、全双工通信 C、流量控制和拥塞控制 D、组播通信 第4章计算机网络与因特网 一、选择题 1．以下关于网卡（包括集成网卡）的叙述中错误的是________。 A.局域网中的每台计算机中都必须安装网卡 B.一台计算机中只能安装一块网卡 C.不同类型的局域网其网卡类型是不相同的 D.每一块以太网卡都有全球唯一的MAC地址 2．计算机网络最主要的作用是________。 A.高速运算 B.提高计算精度 C.传输文本、图像和声音文件 D.实现资源共享 3．IP地址是因特网中使用的重要标识信息，如果IP地址的主机号部分每一位均为0，是指________。 A.因特网的主服务器 B.因特网某一子网的服务器地址 C.该主机所在物理网络本身 D.备用的主机地址 4．下列有关局域网中继器的说法中正确的是________。 A.中继器的工作是过滤掉会导致错误重复的比特信息 B.中继器可以用来连接以太网和令牌环网 C.中继器能够隔离分段之间不必要的网络流量 D.中继器能把收到的信号整形放大后继续传输 5．移动通信系统中关于移动台的叙述正确的是_____。 A.移动台是移动的通信终端，它是收发无线信号的设备，包括手机、无绳电话等 B.移动台就是移动电话交换中心 C.多个移动台相互分割，又彼此有所交叠能形成“蜂窝式移动通信” D.在整个移动通信系统中，移动台作用不大，因此可以省略 6．如果多用户分时系统的时间片固定，那么________，CPU响应越慢。 A.用户数越少 B.用户数越多 C.硬盘容量越小 D.内存容量越大 7．计算机局域网的基本拓扑结构有________。 A.总线型，星型，主从型 B.总线型，环型，星型 C.总线型，星型，对等型 D.总线型，主从型，对等型 8．将异构的计算机网络进行互连所使用的网络互连设备是________。 A.网桥 B.集线器 网站编辑手册 一、网站编辑工作的意义和目的 1.1编辑是做什么的？ 网站编辑是网站运营中的一个重要环节。网站编辑的任务是收集和整理网站相关资料，上传电子版的文章及资料。并能以统筹的眼光分析网站，对网站进行全面的优化。提高网站在搜索引擎上的整体水平、知名度和品牌效应，提高网站的排名和流量，达到客户所提出的要求。 1.2编辑的目的 二、基础篇 2.1搜索引擎 2.1.1什么是搜索引擎 搜索引擎（search engines）是对互联网上的信息资源进行搜集整理，然后供你查询的系统，它包括信息搜集、信息整理和用户查询三部分。 常用的中文搜索引擎：1、https://www.doczj.com/doc/3d18943141.html,2、https://www.doczj.com/doc/3d18943141.html, 2.1.2搜索引擎的特点 常用的两大中文搜索引擎：百度、谷歌。 百度：是全球最大的中文网站、最大的中文搜索引擎。也是目前国内人士用的最多的中文搜索引擎。目前的主要产品有：百度搜索、百度竞价、百度联盟等。 对于文章内容而言，百度更注重文章的原创性，更注重网站的内部结构是否合理、是否有利于访问者的阅读。 从文章更新收录方面来看：百度一般采取先收录再整理的方式。百度随网站的更新速度变化而变化，网站更新速度快，百度抓取速度同样也加快。收录以后，百度将会对收录页面进行整理，并舍弃部分重复的、无用的页面。对于新站不会立刻收录，当新网站有了一个不错的表现，并且有了较多的反向链接，会出现一个阀值，百度判断其网站内容的质量，会开始收录这个新站点内容，这时候网站才会出现来自百度的流量。而百度对于自己的网站(百度知道、百度空间、百度百科等)给予较高的权值。 谷歌: https://www.doczj.com/doc/3d18943141.html,是互联网上5大最受欢迎的网站之一，在全球范围内拥有无数的用户。谷歌更注重用户体验，较之百度更加的公平。但国内访问者较少。 对于文章而言：谷歌同样喜欢原创的内容，比较百度，谷歌更倾向于网站外部链接的多少和质量。谷歌认为外部链接多，并且质量好的网站为好网站。 从文章更新收录方面来看：谷歌收录页面比较的平稳。谷歌能够对网页的重要性做出客观的评价，PageRank并不计算直接链接的数量，而是将链接解释为投票。然后以投票数量来评估该页的重要性，同时也分析网页内容、网页的全部内容以及字体、分区及每个文字精确位置等因素，相邻网页的内容等，然后确定是否收录。谷歌收录后基本能保持稳定的收录量。目前谷歌收录比百度收录较快、较多。 计算机网络试题及答案（一） 一、.填空题 1.所谓计算机网络，会议是利用通信设备和线路将地理位置不同的、功能独立的多个计算机系统互连起来，以功能完善的网络软件实现网络中资源共享和数据通讯的系统。 2.计算机网络如果按作用范围进行分类，可分为广域网（WAN）、局域网（LAN）和城域网（MAN）。 3.网络协议通常采用分层思想进行设计，OSI RM中的协议分为7层，而TCP/IP RM中协议分为4层。 4.在TCP/IP RM中，用于互联层的协议主要有：ARP、IP、RARP、ICMP和IGMP 协议。 5.用于计算机网络的传输媒体有两类：有导线媒体和无导线媒体；光纤可分为两种：单模光纤和多模光纤（MMF）。 6.构成计算机网络的拓扑结构有很多种，通常有星形、总线型、环型、树型、和网状型等。 7.CSMA/CD技术是一种随机接入（所有的用户根据自已的意愿随机地发送数据），冲突不可避免；令牌技术是一种受控接入（各个用户不能任意接入信道而必须服从一定的控制），冲突避免。 8.10BASE-T局域网的数据速率是10mbps，100BASE-TX局域网的数据速率是100mbps。 9.在用双绞线时行组网时，连接计算机和计算机应采用交叉UTP电缆，连接计算机和集线器用直通UTP电缆。 10.在将计算机与10BASE-T集线器进行连接时，UTP电缆的长度不能大于100米。 11.在将计算机与100BASE-TX集线器进行连接时，UTP电缆的长度不能长于100米。 12.以太网交换机和数据交换和转发方式可以分为：直接交换、存储转发交换和改进的直接交换。 13.VLAN的组网方式有两种：静态根据以太网交换机端口进行划分VLAN，动态根据MAC地址、逻辑地址或数据包的协议类型进行划分VLAN。 14.在Internet中，运行IP的互联层可以为其高层用户提供的服务有三个特点：不可靠的数据投递服务、面向无连接的传输服务和尽最大努力投递服务。 15.IP地址由网络号和主机号两部分组成，其中网络号表示互联网中的一个特定网络，主机号表示该网络中主机的一个特定连接。 16.主机的IP地址为202.93.120.77，主机B的IP地址为150.23.55.200。若主机A要向主机B所在的网络进行广播，则直播广播地址为150.23.255.255；若主机A要在本网络中进行广播，则有限广播地址为255.255.255.255。 二、选择题 1.计算机网络是计算机技术和__________相结合的产物。->B A) 网络技术 B) 通信技术 C) 人工智能技术 计算机网络与Internet应用试题及答案 一、是非题 1．分布式处理是计算机网络的特点之一。 A．对 B．错 2．组建一局域网时，网卡是必不可少的网络通讯硬件。 A．对 B．错 3．在IE浏览器中，系统会把我们浏览过的网页保存在缓存的特定文件夹中。 A．对 B．错 4．WWW中的超文本文件是用超文本标识语言写的。 A．对 B．错 5．广域网是一种广播网。 A．对 B．错 6．分组交换网也叫X.25网。 A．对 B．错 7．Yahoo是典型的目录搜索引擎。 A、对 B、错 8．Google就是典型的目录搜索引擎。 A、对 B、错 9．搜索引擎是一个应用程序。 A、对 B、错 10．网络信息安全是一门涉及计算机科学、网络技术、通信技术、密码技术、应用数学、数论、信息论等多种学科的综合性学科。 A、对 B、错 11．对称加密与非对称加密的区别在于加密结果的对称性。 A、对 B、错 12．数字签名是对称加密技术的一种应用。 A、对 B、错 13．计算机协议实际是一种网络操作系统，它可以确保网络资源的充分利用。 A、对 B、错 14．国际标准化组织（ISO）制定的开放系统互联参考模型（OSI）将网络体系结构分成七层。 A、对 B、错 15．Internet是计算机网络的网络。 A、对 B、错 二、单选题 1．按网络的围和计算机之间的距离划分的是______。 A．Windows NT B．WAN和LAN C．星型网络和环型网络 D．公用网和专用网 2．网络的物理拓扑结构可分为______。 A．星型、环型、树型和路径型 B．星型、环型、路径型和总线型 C．星型、环型、局域型和广域型 D．星型、环型、树型和总线型 3．在基于个人计算机的局域网中，网络的核心是______。 一、填空题 1.网络协议主要由三个要素组成：（）、（）和同步。 2.假设两个主机A,B通过一个路由器进行互联，提供主机A和主机B的应用进程之间 通信的层是（），通过主机与主机之间通信的层是（）。 3.通信的目的是传送消息，如语音、文字和图像等。（）是运送消息的实体。 4.在计算机网络中的信道使用多种复用技术，（）是指所有用户在不同的时间 占用相同的频带。（）是指所有的用户在同样的时间占用不同的频带宽度。 5.数据链路层使用的信道主要有两种类型：（）信道和（）信道， 前者最常使用的协议是PPP, 后者最常使用的协议有CSMA/CD。 6.以太网使用CSMA/CD协议可以使很多计算机以多点接入的方式连接在一根总线 上，协议的实质是（）和（）。 7.当网桥刚接入到以太网时，它的转发表是空的，这时若网桥收到一帧数据，网桥就 是按照（）算法处理收到的帧，然后把帧转发出去。 二、选择题 1.IP数据报穿越Internet过程中可能被分片。在IP数据报分片以后，下列哪些设备负 责IP数据报的重组（）。 A.源主机 B.目的主机 C.分片途径的路由器 D.分片途径的路由器和目的主机 2.下列哪个地址属于C类地址（）？ A.141.0.0.0 B.10.10.1.2 C.197.234.111.123 D.225.33.45.56 3.关于RIP协议和OSPF协议，下列说法正确的是（）。 A.都是基于链路状态的外部网关协议。 B.RIP是基于链路状态的内部网关协议，OSPF是基于距离向量的内部网关协议。 C.都是基于距离向量的内部网关协议。 D.RIP是基于距离向量的内部网关协议，OSPF是基于链路状态的内部网关协议。 4.下列哪一个选项不属于路由选择协议的功能？（） A.获取网络拓扑结构的信息。 B.选择到达每个目的网络的最优路径 C.构建路由表 D.发现下一跳的物理地址。 5.每一条TCP连接唯一的被通信两端的两个端点所确定，TCP连接的端点是指 （）。 A.IP地址 B.MAC地址 C.端口号 D.套接字 6.一条TCP连接的建立过程包括（）次握手。 计算机网络试题库 单项选择题 1.1 1. 以下属于物理层的设备是（A） A. 中继器 B. 以太网交换机 C. 桥 D. 网关 [设备] 1.2 2. 在以太网中，是根据___地址来区分不同的设备的（B） A. LLC地址 B. MAC地址 C. IP地址 D. IPX地址 [局域网] 1.3 3. IEEE80 2.3u标准是指（B） A. 以太网 B. 快速以太网 C. 令牌环网 D. FDDI网 [局域网] 1.4 4. 下面哪种LAN 是应用CSMA/CD协议的（C） A、令牌环 B、FDDI C、ETHERNET D、NOVELL [局域网] 1.5 5. FDDI 使用的是___局域网技术。（C） A、以太网； B、快速以太网； C、令牌环； D、令牌总线。 [局域网] 1.6 6. TCP 和UDP 协议的相似之处是（C） A、面向连接的协议 B、面向非连接的协议 C、传输层协议 D、以上均不对 [协议] 1.7 7. 应用程序PING 发出的是___报文。（C） A、TCP 请求报文。 B、TCP 应答报文。 C、ICMP 请求报文。 D、ICMP 应答报文。 [IP协议] 1.8 8. 小于___的TCP/UDP端口号已保留与现有服务一一对应，此数字以上的 端口号可自由分配。（C） A、199 B、100 C、1024 D、2048 [TCP协议——端口] 1.9 9. 当一台主机从一个网络移到另一个网络时，以下说法正确的是（B） A、必须改变它的IP 地址和MAC 地址 B、必须改变它的IP 地址，但不需改动MAC 地址 C、必须改变它的MAC 地址，但不需改动IP 地址 D、MAC 地址、IP 地址都不需改动 [IP协议—网络地址] 1.10 10. IEEE80 2.5 标准是指（C） A、以太网 B、令牌总线网 C、令牌环网 D、FDDI 网 [局域网] 1.11 11. ARP 协议的作用是（D） A、将端口号映射到IP 地址 B、连接IP 层和TCP 层 C、广播IP 地址 D、将IP 地址映射到第二层地址[IP协议—ARP协议] 第四章测验 一、判断 1. 网络中的计算机可能利用微波传输数据，它比利用光缆传输数据的效率高。( F ) 2. 异步转移模式ATM使多种媒体的信息数据可以同时在ATM信道中传输。( ) 3. Internet提供了电子购物服务，因此网络能传递物品。( ) 4. B-ISDN是一种通信网络，数据在其上是模拟信号传输。( ) 5. ADSL是一种网络联结方式，数据在电话线上是模拟信号传输。( ) 6. Internet网由主干网、地区网和校园网（或部门网）三级组成。( ) 7. Inertnet网中计算机的IP地址就是它的主机名。( ) 8. 计算机网络是在通信协议控制下实现的计算机互联。( ) 9. 建立计算机网络的最主要目的是实现资源共享。( ) 10. E-mail帐号能在任意的地点，任意的机器上使用（只要它接入Internet）。( ) 11. 工作站本身所具有的硬盘、光盘、程序、数据、打印机等都是该用户的本地资源，网络上其他工作站和服务器的资源称为网络资源。( ) 12. 蓝牙（IEE802.15）是一种近距离无线通信的技术标准，通过增加发射功率可达到100m，适合于办公室或家庭环境的无线网络。( ) 13. 网络中一台微机既可以作为服务器，也可以作为客户机，取决于它是否同时提供共享资源，又使用其它计算机的资源。( ) 14. 网络信息安全主要是指信息在处理和传输中的泄密问题。( ) 15. 在网络信息安全的措施中，身份认证是访问控制的基础。( ) 16. 在密码学中，所有的公共密钥对所有用户都是公开的。( ) 17. 因特网防火墙的作用主要是防止病毒侵害。( ) 18. 包过滤通常安装在路由器上，而且大多数商用路由器都提供了包过滤的功能。( ) 19. 在一台已感染病毒的计算机上读取一张CD-ROM光盘中的数据，该光盘没有可能被感染病毒。( ) 20. 全面的网络信息安全方案不仅要覆盖到数据流在网络系统中所有环节，还应当包括信息使用者、传输介质和网络等各方面的管理措施。( ) 21. 以太网使用的集线器(Hub)只是扮演了一个连接器的角色，不能放大或再生信号。( ) 22. 使用Cable Modem需要用电话拨号后才能上网。( ) 23. 通过Telnet可以远程使用网上提供该服务功能的计算机系统中的计算资源。( ) 24. 总线式以太网通常采用广播式的通信方式。( ) 25. 计算机广域网与局域网的最本质的区别是网络的覆盖范围不同。( ) 26. 一个完整的URL包括网络信息资源类型／协议、服务器地址、端口号、路径和文件名。( ) 27. 所有的IP地址都可以分配给用户使用。( ) 28. 域名为https://www.doczj.com/doc/3d18943141.html,的服务器，若对应的IP地址为202．119．175．2，则通过主机域名和IP地址都可以实现对服务器的访问。( ) 二、单选 1. 万维网(WWW)引进了超文本的概念，超文本是指_____。 A. 包含链接的文本 B. 包含多种文本的文本 C. 包含图像的文本 D. 包含多种颜色的文本 2. 电子邮件是_____。 A. 通过网页发布的公告信息 B. 网络信息检索服务 C. 一种利用网络交换信息的非实时服务 D. 通过网络实时交互的信息传递方式 教学纲要第二节第三节第一节 第四节知识拓展第五节 教学纲要第二节第三节第一节 第四节知识拓展第五节 计算机网络与Internet 技术第七章 我们可以通过局域网上计算机的资源共享，在英特网上搜索资料，下载、上传文件以及收发电子邮件操作等，学习计算机网络与Internet 技术。 教学纲要第二节第三节第一节 第四节 知识拓展第五节 计算机网络基础知识 Internet 的两种接入方式 网上冲浪，学会新的学习方法 常用网络工具的使用 教学内容： 教学纲要第二节第三节第一节 第四节 知识拓展第五节 记要章节： §7.1 计算机之间的文件共享§7.2 ADSL 接入§7.3 上网搜索信息§7.4 收发电子邮件§7.5下载工具的用法 教学纲要第二节第三节第一节 第四节 知识拓展第五节 ●了解网络互连的方法和技巧●TCP/IP 协议的设置 ●文件共享操作本节任务： 有多台计算机，已连接了局域网，要求各计算机之间共享文件 任务描述：某公司局域网内有多台计算机，为了实现计算机之间的资源共享，经理让您上机进行相关设置，以实现计算机之间的文件共享。 学习目标 教学纲要第二节第三节 第一节第四节知识拓展第五节 操作步骤： 1、检查硬件连接 2．配置网络协议检查网卡是否已经安装？再检查一下网线的两端是否连接到了计算机和集线器，连接正常时，网卡上的指示灯会显示绿灯并有闪烁，而集线器上对应的指示灯也显示绿灯。配置网络协议，确保所有计算机上都安装了TCP/IP ，并且工作正常。打开“资源管理器”，找到“网上邻居”并右击，从快捷菜单中选择“属性”选项，打开“网络连接”窗口。双击本地连接图标，在“本地连接状态”对话框，单击“属性”按钮，在“本地连接属性”对话框中双击Internet 协议（TCP/IP ），在打 开的Internet 协议属性对话框， 根据网络管理规划，配置网络协 议，如右图所示。 网络编辑是指利用相关专业知识及计算机和网路等现代信息技术，从事互联网网站内容建设的人。按照目前的网站数量估计，我国现拥有网络编辑从业人员300余万，在未来十年里，网络编辑职位将呈需求上升趋势，总增长量将超过26%，比其他各类职位的平均增长量还高。 这是一个新兴的职业，2005年，劳动和社会保障部公示了第三批的十种新行业中，"网络编辑员"名列其中，同时也发布了网络编辑的职业标准，推出网络编辑的职业资格考试，考试合格者将获得《专业技术水平认证证书》，作为从业资质。目前的从业人员主要由传统媒体（如报纸杂志，电视、电台）编辑、记者、网站管理员、图文设计等职业中分流出来的。 依据《国家职业标准：网络编辑员》的规定，我们国家现将该职位分为网络编辑员、助理网络编辑师、网络编辑师和高级网络编辑师四个等级。 网络编辑工作有四大特点：超文本链接式编辑特点、全时化编辑特点、数据库化编辑特点、交互性编辑特点。因此她要求从业者有相应的计算机基础，坚强的意志力，敏锐的新闻传媒视野以及良好的户动和沟通技能。 网站编辑工作的挑战主要有如下体现。 从职业本身来说，除了懂得传统的新闻报道，还要了解互联网的网络编辑等技术手段； 网络24小时运营，新闻、体育等编辑人员需要倒班，突发事件要随时报道和跟进，比较辛苦。网络新闻是实时的，对人员的判断力、突发事件处理能力等综合素质要求较高。 网络新闻互动性较强，经常会有网友跟帖讨论，实时关注和讨论。如何与网友互动，把握媒体的舆论导向，对网站编辑是很大的挑战。 网络编辑职业的优势 1、信息传播的灵魂工程师 网络编辑是一个新兴职业，从事网络信息的工作人员--网络编辑师成为不折不扣的网站灵魂工程师。 2、列入国家职业资格大典 劳动和社会保障部与2005年3月24日公示的10个新职业名单中网络编辑名列其中，并已经被列入国家职业分类大典。自05年网络编辑员国家职业资格鉴定考试开始启动至今，网络编辑这个新兴的职业开始受到关注，网络编辑职业资格鉴定也越来越受到瞩目。网络编辑职业资格鉴定考试的推出是很多目前在职的网络编辑的福音。 3、网络编辑需求呈上升趋势 目前，网络编辑从业人员一般是非专业中分流出来的，缺乏统一的职业标准与规范，给 计算机网络技术试题及答案 第一部分选择题 一、单项选择题（本大题共20小题，每小题1分，共20分） 在每小题列出的四个选项中只有一个选项是符合题目要求的，请将正确选项前的字母填在题后的括号内。1．对于带宽为6MHz的信道，若用8种不同的状态来表示数据，在不考虑热噪声的情况下，该信道每秒最多能传送的位数为（） A 36×106 B 18× C 10 C 48×106 D 96×106 2．E1载波的数据传输为（） B 1Mbps D 10Mbps 3．采用8种相位，每种相位各有两种幅度的PAM调制方法，在1200Baud的信号传输速率下能达到的数据传输速率为（） A 2400b/s B 3600b/s C 9600b/s D 4800b/s 4．采用曼彻斯特编码的数字信道，其数据传输速率为波特率的（） A 2倍 B 4倍 C 1/2倍 D 1倍 5．采用海明码纠正一位差错，若信息位为7位，则冗余位至少应为（） A 5位 B 3位 C 4位 D 2位 6．在CRC码计算中，可以将一个二进制位串与一个只含有0或1两个系数的一元多项式建立对应关系。例如，与位串101101对应的多项式为（） A x6+x4+x3+1 B x5+x3+x2+1 C x5+x3+x2+x D x6+x5+x4+1 A DB-25连接器 B DB-9连接器 C DB-15连接器 D RJ11连接器 8．采用AT命令集对Moden进行编程设置，现要让Modem完成“用脉冲拨号呼叫”的操作，则应向Modem 发出的AT命令为（）9．采用RS-232C接口标准连接PC机和Modem，其请求发送信号（RTS）的连接方向为（） A DCE→DTE B DCE→DCE C DTE→DTE D DTE→DCE 10．BSC规程采用的帧同步方法为（） A字节计数法 B 使用字符填充的首尾定界符法 C 使用比特填充的首尾标志法 D 违法编码法 11．采用有序接收的滑动窗口协议，设序号位数为n，则发送窗口最大尺寸为（） A 2n-1 B 2n-1 C 2n D 2n 12．若数据链路的发送窗口尺寸WT=4，在发送3号帧、并接到2号帧的确认帧后，发送方还可连续发送（）A 2帧 B 3帧 C 4帧 D 1帧 13．面向字符的同步控制协议是较早提出的同步协议，其典型代表是（） A IBM公司的二进制同步通信协议BSC 第一节计算机网络和因特网 【教学设计学科名称】 计算机网络和因特网是甘肃教育、甘肃声像出版社出版的初中信息技术七年级教材上册模块四《网络基础》第一节教学内容。 【所在班级情况，学生特点分析】 本节内容的对象是七年级的学生，已经具备了一定的计算机操作能力。大部分学生家里都有计算机可以连入互联网，他们具备了一定的上网经验，对计算机网络有初步的认识。但是，他们对网络的了解大部分是停留在网上聊天、BBS论坛、网络游戏以及有限的资料收集上。总体上讲，学生对网络的构成及相应有应用没有一个系统的了解，更没有形成有意识地利用网络资源帮助学习的意识。因此，学生要学习基本的网络知识，并为下面的网络信息收集打下基础。 【教材内容分析】 本节内容是甘肃教育、甘肃声像出版社出版的初中信息技术七年级教材上册模块四《网络基础》第一节教学内容。本节主要让学生了解计算机网络的组成和分类，了解因特网的产生和发展，掌握因特网提供的主要服务。内容丰富，灵活有趣，实用性很强。既可培养学生学习兴趣，又可帮助学生进一步学会借助信息技术手段解决实际生活问题，提高学生综合应用能力。 【教学目标】 知识与技能：了解什么是计算机网络，计算机网络的分类。 过程与方法：了解因特网的产生、发展过程。 情感态度与价值观：引导学生正确认识网络和合理的使用网络。 【教学重难点分析】 教学重点：计算机网络概念、计算机与网络的分类。 教学难点：正确认识网络。 【教学课时】 1课时 【教学过程】 一、导入新课 同学们，从我们刚开始学习计算机到今天，我们已经把计算机的许多知识和许多应用软件都学进我们大脑的“存储器”。可在今天，随着计算机技术的不断发展和普及，越来越多的计算机已经进入了一个新“世界”，在这个世界里，所有的计算机都是一体的，任何一个计算机都不是孤立的，它们可以相互的交换资料、传递信息、共享文件，把原本遥远的天涯海角变成咫尺天涯！这，就是神奇的计算机网络，下面就让我们一起来看看，什么是计算机网络，它为什么会这么神奇。 二、讲授新课 （一）展示计算机网络图，并定义计算机网络概念：（由教师引导，学生总结） 计算机网络试卷及参考答案 （本卷考试时间150分钟） 一、填空（每空1分，共30分） 1、一个计算机网络典型系统可由____资源____子网和____通信____子网组成。 2、数字数据是____数字信号_____的值。 3、调制速率是指调制信号状态的每秒转换____次数____，其度量单位是____波特____。 4、模拟信号传输的基础是_____载波_____，它是频率____恒定_____的连续信号，它不能直接 传输____基带______信号。 5、日常使用的无线传输媒体有三种：_____微波_____、_____红外线_____和_____激光_____。 6、在OSI参考模型中，传输层的紧邻上层是_____会话_____层，紧邻下层是____网络____层。 7、局域网协议把OSI为数据链路层分为____MAC____子层和_____LLC_____子层。 8、TCP/IP网的IP协议的基本任务是通过互连网传送____数据报____。 9、连接公用电话的MODEM解调器将模拟信号（音频信号）解调成____数据信号____。 10、用以使发送方确定接收方是否正确收到了由它发送的数据信息的方法称为__反馈检测法__。 11、数据链路层基本任务是将源机网络层来的数据可靠地传输到__相邻节点__的目标机网络层。 12、虚电话服务是通信子网向____端系统____提供的网络服务。 13、数据报服务一般仅由____数据报交换网____提供。 14、OSI模型的表示层主要负责处理数据的___语法表示问题___。 15、在NOVELL网络中，要查看或修改目录的属性，可用____FLAGDIR____命令。 16、在NOVELL网络中，要查看实际权限和受权人，可用____RIGHT____命令。 17、在网络环境下，配备大容量外存储器的服务器，称为____磁盘____服务器。 18、请填写光纤分布数据接口FDDI信息帧格式或各字段 前导码起始定界符帧控制目的地址源地址 LLC或站管理信息帧检验序列结束定界符 FS 二、单项选择题（每小题1分，共10分） 1、不适合交互式通信的交换技术是（A） A、报文 B、分组 C、电路 D、虚电路分组 2、所有站点均连接到公共传输媒体上的网络结构是（A） A、总线型 B、环型 C、树型 D、混合型 3、n中取m的定比码编码效率为（D） A、m/n B、C log2m/n C、 m/(n+m)D、log2C n m n m 4、在ISO层次体系中，实现同步进程间对话是（ D ） A、运输层 B、应用层 C、表示层 D、会话层 5、EIA RS-232C的“1”信号电平是（D） A、0至+5伏 B、+5至+15伏 C、-5至0伏 D、-15至-5伏 6、实现通信协议的软件一般固化在（C）的ROM中 A、微机主板 B、IDE卡 C、网卡 D、MODEM卡 7、在多个数据字符的数据块之前以一个或多个同步字符作为开始，帧尾是另一个控制字符， 这种传输方案称为（A） A、面向字符的同步传输 B、异步传输 C、面向位同步传输 D、起止式传输 8、若一物理媒体能达到的位传输速率为64Kbps，采用脉码调制方法对模拟信号进行编码， 每次采样使用256个量化级进行量化，那么允许每秒钟采样的次数是（D） A、256次 B、512次 C、128次 D、8000次 9、ELA RS-232C的电气特性规定逻辑“0”的电平电压为（A） A、+5至+15伏 B、0至+5伏 C、-5至0伏 D、-15至-5伏 计算机网络考试试题纸B卷 一、单选题（每小题1分，共20分） 1．调制解调技术主要用于下列哪种数据通信中 A、模拟信号传输模拟数据 B、模拟信号传输数字数据 C、数字信号传输数字数据 D、数字信号传输模拟信号 2．下列哪种交换方法传输延迟最小？ A、报文分组交换 B、报文交换 C、电路交换 D、各种方法都一样 3．下列哪种交换方法使用了虚电路？ A、报文分组交换 B、报文交换 C、电路交换 D、各种方法都一样 4．虚电路方法在传输数据前 A、必须预先建立一条逻辑连接 B、不需要对信息进行分组 C、收发两站的发送接收设备必须同时可用 D、必须建立起专用的通信线路 5．在下列传输介质中，哪种介质的典型传输率最高？ A、双绞线 B、同轴电缆 C、光纤 D、无线介质 6．RS232C逻辑0的电平为 A、大于+3V B、小于-3V C、大于+15V D、小于-15V 7．两端用户传输文件，应属于下列OSI的哪一层处理？ A、表示层 B、会话层 C、传输层 D、应用层 8．决定使用哪条路径通过子网，属于下面OSI的哪一层处理？ A、物理层 B、数据链路层 C、传输层 D、网络层 9．OSI模型中，对话控制是哪个层次的功能？ A、网络层 B、传输层 C、会话层 D、表示层 10．管理计算机通信的规则称为： A、协议 B、介质 C、服务 D、网络操作系统 11．控制访问网络资源的软件称为 A、操作系统 B、工作站 C、客户机 D、外设 12．Windows NT为管理用户帐号提供的使用程序叫做 A、服务器管理器 B、用户管理器 C、域用户管理器 D、帐号管理器 13．以下哪个IP地址属于C类地址？ A、 B、C、 D、14，域名与下面哪个一一对应 A、物理地址 B、IP地址 C、网络 D、以上均错 15．路由器运行于OSI模型的哪个层次？ A、数据链路层 B、网络层 C、传输层 D、应用层 16．IP协议提供哪种服务？ A、无连接服务 B、面向连接的服务 C、虚电路服务 D、以上都不是 17．DNS必须具有一个 A、动态IP地址 B、静态IP地址 C、动态计算机名 D、固定的计算机名 18．下面哪个网络技术最适合多媒体通信需要？ A、 B、ISDN C、帧中继D、TAM 19．报文分组交换方式使用于下列哪种负荷情况？ A、间歇式轻负荷 B、传输数据率需固定的负荷 C、持续的实时要求高的负荷 D、中等或大量随时要传送的负荷计算机网络与Internet教程试题
《计算机网络基础与Internet应用习题参考答...
计算机网络试题及答案最新版
第4章 计算机网络与因特网
计算机网络基础与Internet应用
计算机网络期末考试试卷及答案
第4章 计算机网络与因特网
网络编辑培训资料
计算机网络期末考试试题及答案
计算机网络与Internet应用试题及答案
计算机网络试题(含答案)
计算机网络试题库含答案
第四章(计算机网络与因特网)测验及答案
《计算机应用基础》第7章 计算机网络与Internet技术[PPT教案]
网络编辑的优势和特点
计算机网络试题及答案
第一节 计算机网络和因特网
计算机网络试卷及参考答案
计算机网络试题及答案
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