M3Q13: TCP, UDP, & Ports

Question 1

A TCP or UDP port specifies a particular service or application

A. True
B. False

Answer 1

A. True

Explanation: In order for applications and protocols to use the network they must be attached to a TCP or UDP port. In this way the port number being used specifies the application or protocol which uses that specific port.

Question 2

What port number is used for HTTPS (Hyper Text Transfer Protocol Secure)?

A. 80
B. 23
C. 22
D. 443

Answer 2

D. 443

Explanation: 443 is the well known port for HTTPS which is Hyper Text Transfer Protocol Secure.

Question 3

A common web server hosting an unsecure website would be listening on which TCP port?

A. 80
B. 23
C. 22
D. 443

Answer 3

A. 80

Explanation: 80 is the well known port for HTTP which is Hyper Text Transfer Protocol without security.

Question 4

The range of ports from 0 to 1023 are reserved for specific protocols and applications that are widely used. These ports are known as ___________________.

A. Basic Ports
B. Registered Ports
C. Well Known Ports
D. Private Ports

Answer 4

C. Well Known Ports

Explanation: The ports in the range of 0 – 1023 are the Well Known Ports. These are mapped to specific protocols that are widely used and the port numbers cannot be changed.

Question 5

Transmission Control Protocol (TCP) uses which method to establish a connection-oriented session?

A. 1-way Handshake
B. 2-way Handshake
C. 3-way Handshake
D. 4-way Milkshake

Answer 5

C. 3-way Handshake

Explanation: The 3-way Handshake is how TCP sets up a connection-oriented session. It’s called a 3-way Handshake because it includes 3 messages that set up the connection: a SYN, a SYN+ACK, and then an ACK.

Question 6

Which TCP port number is used by SSH (Secure Shell)?

A. 20
B. 22
C. 23
D. 443

Answer 6

B. 22

Explanation: Secure Shell is the most popular secure remote terminal session protocol and uses TCP port 22.

Question 7

Which TCP port number is used by Telnet?

A. 20
B. 21
C. 23
D. 143

Answer 7

C. 23

Explanation: Telnet is the most popular unsecure remote terminal session protocol and uses TCP port 23. *In most scenarios Telnet should not be used and SSH should be used instead.

Question 8

File Transfer Protocol (FTP) uses two port number to setup an FTP connection and transfer files. The ports used by FTP are ports 21 and ____.

A. 20
B. 21
C. 31
D. 143

Answer 8

A. 20

Explanation: FTP uses ports 20 (FTP data transfer) and 21 (FTP control).

Question 9

Which command can be used on a computer to check the TCP and UDP sessions currently open on the computer?

A. telnet
B. netstat
C. netshell
D. network

Answer 9

B. netstat

Explanation: The “netstat” command lists all ports currently open on a computer and the common switches are –a, -b, -n, -o, and –r.