Chapter 5: Ports, Protocols & Network Devices

Question 1

Transmission Control Protocol (TCP) establishes network connections with a 3-way handshake, a process that includes these 3 steps:

Answer 1

1. SYN: The client computer attempts to initiate a session to a server with a synchronization packet of information (SYN packet)
2. SYN + ACK: The server responds to the client request by sending a synchronization/acknowledgement packet (SYN-ACK packet)
3. ACK: The client sends an acknowledgment packet (ACK packet) to the server

Question 2

What is Transmission Control Protocol (TCP)?

Answer 2

TCP is a network session protocol that is known as a connection-oriented session

This means that every packet that is sent is checked for delivery. If the receiving computer doesn’t receive a packet, it cannot assemble the message and will ask the sending computer to transmit the packet again.

Question 3

How does User Datagram Protocol (UDP) work?

Answer 3

UDP sessions are known as connectionless sessions

In this case, if a packet is dropped, it is not asked for again.

Example: Streaming Media

Question 4

You’re looking for a website, you type the name of that website into the address bar of a web browser and one of two HTTP/HTTPS protocols will be initiated, which port numbers will be used?

Answer 4

If the website uses HTTP (No security), it will use port number 80

If the website uses HTTPS (security), it will use port number 443

Question 5

What are the roles of the SMTP, POP3 and IMAP protocols?

Answer 5

SMTP - ‘send mail to people’
POP3 - retrieving mail from people
IMAP - ability for mail to remain on the server and be accessed from anywhere

Question 6

You need to communicate with an external host to send and receive files and/or run commands on the external host, what protocols would you use?

Answer 6

FTP (File Transfer Protocol) or SSH (Secure Shell)

Question 7

What are the port numbers associated with FTP (File Transfer Protocol)?

Answer 7

When you connect to an FTP server, that FTP server will have port 989 and 990 open (SFTP), a less secure port that’s less used is port 21

Question 8

What is SSH and what does it do?

Answer 8

SSH stands for Secure Shell

Secure Shell (SSH) enables data to be exchanged between computers on a secured channel (more secure then FTP)

Question 9

You want to utilize SSH, which port number will you likely use?

Answer 9

The SSH server housing the data you want to access would have port 22 open

Question 10

You’re setting up a SOHO network, what protocol would you use to automatically assign IP addresses to hosts?

Answer 10

Dynamic Host Configuration Protocol (DHCP)

Question 11

What does each letter of DORA stand for in regards to DHCP?

Answer 11

Discovery - Client discovers DHCP server

Offering - Server offers IP address

Request - Client picks and request IP

Acknowledgement - Server Acknowledges the request, client can use IP address for set amount of time