The internet structure: The TCP/IP Stack

Question 1

What does TCP/IP stand for?

Answer 1

Transmission Control Protocol/Internet Protocol

Question 2

What are the 4 layers in the TCP/IP stack?

Answer 2

• Application layer
• Transport layer
• Network layer
• Link layer

Question 3

What happens in the application layer?

Answer 3

The application layer is based at the top of the stack. It specifies what
protocol needs to be used in order to relate the application that’s being sent
- E.g. Browser application - protocol HTTP

Question 4

What happens in the transport layer?

Answer 4

• The transport layer uses TCP to establish an end-to-end connection
  between the source and recipient computer
• The transport layer splits data up into packets and labels these packets with
  their packet number, the total number of packets the original data was split
  up into and the port number being used for communication
• If any packets get lost, the transport layer requests re-transmissions of these
  lost packets

Question 5

What happens in the network layer?

Answer 5

• The network layer adds the source and destination IP addresses
• Routers operate on the network layer and the router is what uses the IP
  addresses to forward the packets.
• The sockets are then used to specify which device the packets must be sent
  to and the application being used on that device

Question 6

What happens in the link layer?

Answer 6

The link layer is the connection between the network devices, it adds the
MAC address identifying the Network Interface Cards of the source and
destination computers