CCNA NETACAD 14-15 EXAM PREP

Which action is performed by a client when establishing communication with a server via the use of UDP at the transport layer?

• The client sets the window size for the session.

• The client sends an ISN to the server to start the 3-way handshake.

• The client randomly selects a source port number.

• The client sends a synchronization segment to begin the session.

Which transport layer feature is used to guarantee session establishment?

• UDP ACK flag

• TCP 3-way handshake

• UDP sequence number

• TCP port number

What is the complete range of TCP and UDP well-known ports?

• 0 to 255

• 0 to 1023

• 256 – 1023

• 1024 – 49151

What is a socket?

• the combination of the source and destination IP address and source and destination Ethernet address

• the combination of a source IP address and port number or a destination IP address and port number

• the combination of the source and destination sequence and acknowledgment numbers

• the combination of the source and destination sequence numbers and port numbers

A PC is downloading a large file from a server. The TCP window is 1000 bytes. The server is sending the file using 100-byte segments. How many segments will the server send before it requires an acknowledgment from the PC?

• 1 segment

• 10 segments

• 100 segments

• 1000 segments

Answer explanation

Explanation: With a window of 1000 bytes, the destination host accepts segments until all 1000 bytes of data have been received. Then the destination host sends an acknowledgment.

Which factor determines TCP window size?

• the amount of data to be transmitted

• the number of services included in the TCP segment

• the amount of data the destination can process at one time

• the amount of data the source is capable of sending at one time

Answer explanation

Explanation: Window is the number of bytes that the sender will send prior to expecting an acknowledgement from the destination device. The initial window is agreed upon during the session startup via the three-way handshake between source and destination. It is determined by how much data the destination device of a TCP session is able to accept and process at one time.

What does a client do when it has UDP datagrams to send?

• It just sends the datagrams.

• It queries the server to see if it is ready to receive data.

• It sends a simplified three-way handshake to the server.

• It sends to the server a segment with the SYN flag set to synchronize the conversation.

Answer explanation

Explanation: When a client has UDP datagrams to send, it just sends the datagrams.

Which three fields are used in a UDP segment header? (Choose three.)

• Acknowledgment Number

• Length

• Window Size

• Source Port

• Checksum

Answer explanation

Explanation: A UDP header consists of only the Source Port, Destination Port, Length, and Checksum fields. Sequence Number, Acknowledgment Number, and Window Size are TCP header fields.

What are two roles of the transport layer in data communication on a network? (Choose two.)

• identifying the proper application for each communication stream

• providing frame delimiting to identify bits making up a frame

• tracking the individual communication between applications on the source and destination hosts

• performing a cyclic redundancy check on the frame for errors

• providing the interface between applications and the underlying network over which messages are transmitted

Answer explanation

Explanation: The transport layer has several responsibilities. The primary responsibilities include the following:

- Tracking the individual communication streams between applications on the source and destination hosts.

- Segmenting data at the source and reassembling the data at the destination.

- Identifying the proper application for each communication stream through the use of port numbers

What information is used by TCP to reassemble and reorder received segments?

• port numbers

• sequence numbers

• acknowledgement numbers

• fragment numbers

Answer explanation

Explanation: At the transport layer, TCP uses the sequence numbers in the header of each TCP segment to reassemble the segments into the correct order.