ITN Unit 14

Which scenario describes a function provided by the transport layer?

• A student is using a classroom VoIP phone to call home. The unique identifier burned into the phone is a transport layer address used to contact another network device on the same network.

• A student is playing a short web-based movie with sound. The movie and sound are encoded within the transport layer header.

• A student has two web browser windows open in order to access two web sites. The transport layer ensures the correct web page is delivered to the correct browser window.

• A corporate worker is accessing a web server located on a corporate network. The transport layer formats the screen so the web page appears properly no matter what device is being used to view the web site.

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 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

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

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

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.)

• Window Size

• Length

• Source Port

• Acknowledgment Number

• Checksum

Answer 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.

Which two characteristics are associated with UDP sessions? (Choose two.)

• Destination devices receive traffic with minimal delay.

• Transmitted data segments are tracked.

• Destination devices reassemble messages and pass them to an application.

• Received data is unacknowledged.

• Unacknowledged data packets are retransmitted.

Which protocol or service uses UDP for a client-to-server communication and TCP for server-to-server communication?

• HTTP

• FTP

• DNS

• SMTP

Answer explanation

Some applications may use both TCP and UDP. DNS uses UDP when clients send requests to a DNS server, and TCP when two DNS serves directly communicate.

Which category does port 1025 fall into?

• Well-Known Ports

• Registered Ports

• Private/Dynamic Ports

Answer explanation

Well-Known Ports - 0-1023

Registered Ports - 1024-49,151

Private/Dynamic Ports - 49,152-65,535