Serving applications - Multiple Choices Questions - [CNP3] Computer Networking : Principles, Protocols and Practice

Câu hỏi 1: The transport services

The services play an important role in computer networks since they define what the user can really expect. Selection all the correct affirmations about the connectionless network service ?

The connectionless network service will never deliver twice the same SDU to a given destination.

The connectionless network service may never deliver some SDUs to their destination.

The connectionless network service may deliver the same SDU several times to a given destination.

The connectionless network will always deliver SDUs in order at their destination.

The connectionless network service may deliver corrupted SDUs at their destination

The connectionless network service can transfer SDUs of limited size

Câu hỏi 2: The connection-oriented service: user interactions

The connection-oriented service is perhaps the most widely used transport service. The interactions between the user of the service and the underlying protocol can be represented as the exchange of various primitives. Considering the interactions between a user of the connection-oriented transport service and its provider, which of the following affirmations are correct? Select all the correct ones.

A Connect.request primitive is issued by the user to request the establishment of a connection.

A user that has accepted a connection cannot issue a Data.request until the delivery of a Connect.confirm to the connection initiator.

To refuse the establishment of a connection, a user responds to a Connect.indication primitive with a Disconnect.request primitive.

A user that has initiated a connection cannot issue a Data.request before having received a Connect.confirm primitive.

A service provider may issue a Disconnect.indication primitive on an established connection at any time.

To confirm the establishment of a connection, a user responds to a Connect.request primitive by issuing a Connect.response primitive.

A user that has received a Connect.indication primitive can immediately issue Data.request primitives to send data over the connection.

A Connect.request primitive issued by a user can be followed by a Disconnect.indication issued by the service provider.

The service provider issues a Connect.indication primitive to indicate that it has received a connection establishment attempt.

A user that has accepted a connection can issue a Data.request immediately after having issued the Connect.response primitive.

Câu hỏi 3: The connection-oriented transport service

Consider the connection-oriented transport service. Among the following affirmations about this service, select the ones that are correct.

An abrupt connection release may cause some SDUs to be discarded.

When a user issues a graceful Disconnect.request, only one direction of transfer is closed.

A transport service provider may issue a Disconnect.indication at any time to terminate a connection.

A transport service provider may itself issue a Disconnect.indication to gracefully terminate a connection.

A transport service provider may issue a Data.indication primitive to a user after having received a graceful Disconnect.request from this user.

A user may issue a Data.request after having received a graceful Disconnect.indication.

With a message-mode service, each Data.request issued by one user will lead to a Data.indication at the other end.

A user may issue a Data.request after having issued a graceful Disconnect.request.

Câu hỏi 4: The network layer

Which of the following affirmations correspond to the behaviour of the network layer ? Select all the correct ones.

The network layer may loose packets.

The network layer will never deliver a given packet twice.

The network layer may deliver the same packet several times to a given destination.

The network layer may modify the content of packets.

Câu hỏi 5: Connectionless transport

Which of the following mechanisms are likely to be used inside a protocol that provides the unreliable connectionless transport service running on top of an unreliable connectionless network layer? Select all the applicable mechanisms.

Selective repeat.

Sequence numbers to detect out-of-order data.

A CRC to detect transmission errors.

A checksum to detect transmission errors.

A retransmission timer to retransmit lost data.

Port numbers to identify the communicating applications.

Câu hỏi 6: The three-way handshake

The three-way handshake allows successfully negotiating the establishment of a transport connection. Among the following time-sequence diagrams, which is the one that corresponds to a valid three-way handshake ?

Câu hỏi 7: The three-way handshake: possible scenarios

The three-way handshake allows successfully negotiating the establishment of a transport connection. Consider a transport connection that begins which the exchange of two segments as shown in the figure below.

Consider what happens after the exchange of these two segments. Only one of the affirmations below is correct. Which one ?

If Host B receives again CR(seq=12345), it will discard the duplicate segment.

If Host B receives CR(seq=12345), it will respond with CA(seq=56789,ack=12345).

At this stage, the connection is established and all CA segments that arrive should be considered as duplicate and discarded.

Hạn chót	Không có hạn chót
Giới hạn nộp bài	Không có giới hạn
Các tag chuyên mục	transport

Thông tin

Tags

Đăng nhập