Chapter 5 - Fundamentals of TCP/IP Transport and Applications

Question 1

Which of the following header fields identify which TCP/IP application gets data received by the computer?
(Choose two answers.)

a. Ethernet Type
b. SNAP Protocol Type
c. IP Protocol
d. TCP Port Number
e. UDP Port Number

Answer 1

D and E.

Many headers include a field that identifies the next header that follows inside a message. Ethernet uses the Ethernet Type field, and the IP header uses the Protocol field. The TCP and UDP headers identify the application that should receive the data that follows the TCP or UDP header by using the port number field in the TCP and UDP headers, respectively.

Question 2

Which of the following are typical functions of TCP?
(Choose four answers.)

a. Flow control (windowing)
b. Error recovery
c. Multiplexing using port numbers
d. Routing
e. Encryption
f. Ordered data transfer

Answer 2

A, B, C, and F.

IP, not TCP, defines routing. Many other protocols define encryption, but TCP does not. The correct answers simply list various TCP features.

Question 3

Which of the following functions is performed by both TCP and UDP?

a. Windowing
b. Error recovery
c. Multiplexing using port numbers
d. Routing
e. Encryption
f. Ordered data transfer

Answer 3

C.

TCP, not UDP, performs windowing, error recovery, and ordered data transfer. Neither performs routing or encryption.

Question 4

What do you call data that includes the Layer 4 protocol header, and data given to Layer 4 by the upper layers, not including any headers and trailers from Layers 1 to 3?
(Choose two answers.)

a. L3PDU
b. Chunk
c. Segment
d. Packet
e. Frame
f. L4PDU

Answer 4

C and F.

The terms packet and L3PDU refer to the header plus data encapsulated by Layer 3. Frame and L2PDU refer to the header (and trailer), plus the data encapsulated by Layer 2. Segment and L4PDU refer to the header and data encapsulated by the transport layer protocol.

Question 5

In the URI http://www.certskills.com/ICND1, which part identifies the web server?

a. http
b. www.certskills.com
c. certskills.com
d. http://www.certskills.com
e. The file name.html includes the hostname

Answer 5

B.

Note that the hostname is all the text between the // and the /. The text before the // identifies the application layer protocol, and the text after the / represents the name of the web page.

Question 6

Fred opens a web browser and connects to the www.certskills.com website. Which of the following are typically true about what happens between Fred’s web browser and the web server?
(Choose two answers.)

a. Messages flowing toward the server use UDP destination port 80.
b. Messages flowing from the server typically use RTP.
c. Messages flowing to the client typically use a source TCP port number of 80.
d. Messages flowing to the server typically use TCP.

Answer 6

C and D.

Web traffic uses TCP as the transport protocol, with HTTP as the application protocol. As a result, the web server typically uses well-known TCP port 80, which is the well-known port for HTTP traffic. Messages flowing to the web server would have a destination TCP port of 80, and messages flowing from the server would have a source TCP port of 80.