Internet basics

A unique numerical identifier assigned to each device connected to a network. Can be in form IPv4 with 32-bit address IPv6 with 128-bit address

Domain needs to be accessed from public Internet. Each domain is assigned a globally unique name within the DNS The DNS server are dedicated servers that contain list of domain names and their IP address

The computer will ask for the domain name, the server will then respond with an IP address that allow the computer to communicate with

Segmented into geographical groups or levels

Fully Qualified Domain Name It is a domain name that is completely specified on all labels of the hierarchy E.g. www.bbc.co.uk = FQDN

At the most right

Organisation that are responsible for allocating IP addresses to specific domain names

Used to specify means of accessing a resource and its location across a network.

When a client sends a DNS query for the domain to its specified DNS server If the DNS server does not have a record it will either recursively handle the request so can deliver an IP address OR refers to a DNS server authoritative and refers to a lower-level DNS server

Small data They have a trailer, payload, header

Recipients address Sender address Packet number and total packets Time to live or hop limit

Checksum or Cyclical redundancy test

Developed to allow communications to be shared so when one communication was unavailable a different one could be used

Time taken to transfer a packet

Routers forwards data packets from one network to another

They look up the destination IP and finds the best router to forward to It will continuously do this until it reaches its destination

A gateway is needed where data is travelling from one node to another that uses different protocols. Or if network uses different transmission medium

Header data is removed and reapplied with the correct format