Layers

Question 1

Application layer

Answer 1

• This is the layer where the communication process begins
• The application layer interacts directly with software applications, such as web browsers and email clients
• The application layer prepares data for transmission over the network by converting it into a format that can be sent and received over the network (known as encapsulation)

Question 2

Transport layer

Answer 2

• The transport layer receives data from the application layer
• The transport layer is responsible for end-to-end communication between the source and destination
• The transport layer breaks the data it receives down into smaller units called packets
• Each packet is assigned a port number (so the data can be reassembled in the correct order at the destination)
• Each packet is also labelled with a header containing information (e.g. the packet number)

Question 3

Internet layer

Answer 3

• The internet layer receives packets from the transport layer
• It adds a header to each packet, including the sender’s IP address and the receiver’s IP address
• The internet layer is responsible for routing each packet across the network using the IP addresses in the headers

Question 4

Link layer

Answer 4

• receives packets from the Internet layer and prepares them for transmission over the physical network
• The link layer translates the digital packets into an electrical, optical, or wireless signal that can be sent over the network
• Once the signal reaches the receiving end, the network layer translates it back into digital packets