21 - TCP/IP Stack: Transport Layer

Question 1

What is the Transport Layer?

Answer 1

In short: Breaks files into segments or datagrams & provides addresses/port info + reconstitutes packets on the other end

The service browsers and web serves need to provide:

• The specifics of where the data is going to
• Responsible for getting the data from Process A to Process

Question 2

Two types of messages at the Transport Layer level

Answer 2

1. Datagram (TCP)
2. Segment (UDP)

Question 3

What is a Port?

Answer 3

A port is the destination of where data is going

i.e. web information from google will go to a specific port in your computer

• Types of ports
  
  • Web servers (HTTP) - 80
  • Secure web (HTTPS) - 443
  • DNS - 53
  • Secure Shell (SSH) - 22

Question 4

What does TCP stand for?

Answer 4

Transmission Control Protocol

Question 5

What does the TCP do?

Answer 5

Rules used for communications between machines

• Connection oriented
  
  • Three-way handshake
  • Handshake also used to terminate a connection
• Slow, but reliable in receiving and transmitting data

Question 6

What does UDP stand for?

Answer 6

User Data Protocol

Question 7

What does UDP do?

Answer 7

Fast, but unreliable

• Connectionless
  
  • No three-way handshake
• Packets not guaranteed to arrive or arrive in order

Question 8

What does the Default Gateway do?

Answer 8

Router that provides access to networks outside of the local network (i.e. the Internet)