ICND1 – TCP & UDP Questions

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Question 1

[am4show have=’p2;’]Which of the following are types of flow control? (Choose three)

A. buffering
B. cut-through
C. windowing
D. congestion avoidance
E. load balancing

 

Answer: A C D[/am4show]

Explanation

Three types of flow control are buffering, windowing & congestion avoidance:

+ Buffering: If a device receives packets too quickly for it to handle then it can store them in a memory section called a buffer and proceed them later.

+ Windowing: a window is the quantity of data segments that the transmitting device is allowed to send without receiving an acknowledgment for them. For example:

With the window size of 1, the sending device sends 1 segment and the receiving device must reply with 1 ACK before the sending device can send the next segment. This “waiting” takes some time.

By increasing the window size to 3, the sending device will send up to 3 segments before waiting an ACK -> helps reduce the waiting time.

+ Congestion avoidance: lower-priority traffic can be discarded when the network is overloaded -> minimize delays.

Question 2

[am4show have=’p2;’]A receiving host has failed to receive all of the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?

A. decrease the window size
B. use a different source port for the session
C. decrease the sequence number
D. obtain a new IP address from the DHCP server
E. start a new session using UDP

 

Answer: A[/am4show]

Question 3

[am4show have=’p2;’]What must occur before a workstation can exchange HTTP packets with a web server?

A. A UDP connection must be established between the workstation and its default gateway.
B. A UDP connection must be established between the workstation and the web server.
C. A TCP connection must be established between the workstation and its default gateway.
D. A TCP connection must be established between the workstation and the web server.
E. An ICMP connection must be established between the workstation and its default gateway.
F. An ICMP connection must be established between the workstation and the web sewer.

 

Answer: D[/am4show]

Explanation

HTTP is based on TCP connection so a TCP connection must be established first between the workstation and the web server.

Question 4

[am4show have=’p2;’]How does TCP differ from UDP? (Choose two)

A. TCP provides best effort delivery.
B. TCP provides synchronized communication.
C. TCP segments are essentially datagrams.
D. TCP provides sequence numbering of packets.
E. TCP uses broadcast delivery.

 

Answer: B D[/am4show]

Explanation

Before two computers can communicate over TCP, they must synchronize their initial sequence numbers (ISN) -> B is correct.

TCP uses a sequence number to identify each byte of data. The sequence number identifies the order of the bytes sent from each computer so that the data can be reconstructed in order, regardless of any fragmentation, disordering, or packet loss that may occur during transmission -> D is correct.

Question 5

[am4show have=’p2;’]What is the purpose of flow control?

A. To ensure data is retransmitted if an acknowledgement is not received.
B. To reassemble segments in the correct order at the destination device.
C. To provide a means for the receiver to govern the amount of data sent by the sender.
D. To regulate the size of each segment.

 

Answer: C[/am4show]

Question 6

[am4show have=’p2;’]Refer to the exhibit. A network technician has added host A to the network. Host A cannot communicate on the network. A ping that is issued on the host to address 127.0.0.1 fails. What is the problem?

A. The router is not forwarding the ping packets to network 127.0.0.0.
B. The remote host at 127.0.0.1 is unreachable.
C. The default gateway is incorrect.
D. The IP address of host A is incorrect.
E. The TCP/IP protocols are not loaded.

 

Answer: E[/am4show]