Compare Protocols and Ports

Question 1

Transmission Control Protocol

Answer 1

Any given packet could be damaged or fail to arrive due to faults or network congestion. TCP provides several mechanisms to overcome this lack of reliability. It is described as a “connection-oriented” protocol.

• Establishes a connection between the sender and recipient using a handshake sequence of SYN, SYN/ACK, and ACK packets.

-Assigns each packet a sequence number so that it can be tracked.

-Allows the receiver to acknowledge (ACK) that a packet has been received.

-Allows the receiver to send a negative acknowledgement (NACK) to force retransmission of a missing or damaged packet.

-Allows the graceful termination of a session using a FIN handshake.

TCP is used when the application protocol cannot tolerate missing or damaged information.

Two application protocols that use TCP
-HyperText Transfer Protocol (HTTP)
& HyperText Transfer Protocol Secure (HTTPS)

-Secure Shell (SSH)

Question 2

User Datagram Protocol

Answer 2

Sometimes it is more important that communications be faster than they are reliable.
The User Datagram Protocol (UDP) is a connectionless , non-guaranteed method of communication with no sequencing or acknowledgements.
UDP is suitable for applications that do not require acknowledgement of receipt and can tolerate missing or out-of-order packets. It is often used by applications that transfer time-sensitive data but do not require complete reliability, such as voice or video.
Two examples of protocols that use UDP are:
- Dynamic Host Configuration Protocol (DHCP).
- Trivial File Transfer Protocol (TFTP).

Question 3

PORT 20 TCP

Answer 3

File Transfer Protocol (FTP)—Data connection

Make files available for download across a network (data connection port)

Question 4

PORT 21 TCP

Answer 4

File Transfer Protocol (FTP)—Control connection

Make files available for download across a network (control connection port)

Question 5

PORT 22 TCP

Answer 5

Secure Shell (SSH)

Make a secure connection to the command-line interface of a server

Question 6

PORT 23 TCP

Answer 6

Telnet

Make an unsecure connection to the command-line interface of a server

Question 7

PORT 25 TCP

Answer 7

Simple Mail Transfer Protocol (SMTP)

Transfer email messages across a network

Question 8

PORT 53 TCP/UDP

Answer 8

Domain Name System (DNS)

Facilitate identification of hosts by name alongside IP addressing

Question 9

PORT 67 UDP

Answer 9

Dynamic Host Configuration Protocol (DHCP) Server

Provision an IP address configuration to clients

Question 10

PORT 68 UDP

Answer 10

DHCP Client

Request a dynamic IP address configuration from a server

Question 11

PORT 80 TCP

Answer 11

HyperText Transfer Protocol (HTTP)

Provision unsecure websites and web services

Question 12

PORT 110 TCP

Answer 12

Post Office Protocol (POP)

Retrieve email messages from a server mailbox

Question 13

PORT 137 - 139 UDP/TCP

Answer 13

NetBIOS over TCP/IP

Support networking features of legacy Windows versions

Question 14

PORT 143 TCP

Answer 14

Internet Mail Access Protocol (IMAP)

Read and manage mail messages on a server mailbox

Question 15

PORT 161 UDP

Answer 15

Simple Network Management Protocol (SNMP)

Query status information from network devices

Question 16

PORT 162 UDP

Answer 16

SNMP trap operation

Report status information to a management server

Question 17

PORT 389 TCP

Answer 17

Lightweight Directory Access Protocol (LDAP)

Query information about network users and resources

Question 18

PORT 443 TCP

Answer 18

HTTP Secure (HTTPS)

Provision secure websites and services

Question 19

PORT 445 TCP

Answer 19

Server Message Block (SMB)

Implement Windows-compatible file and printer sharing services on a local network (also sometimes referred to as Common Internet File System [CIFS])

Question 20

PORT 3389 TCP

Answer 20

Remote Desktop Protocol (RDP)

Make a secure connection to the graphical desktop of a computer