DNS

Notes:
DNS translates a URL into an IP address.
Browser and OS will determine if it knows the IP address from memory or cache.
If not, OS queries resolving name server for IP address
RNS communicates with root name servers for IP address
Which will link to the Top Level Domain name servers
RNS stores info from Root Name Servers in cache
Resolving queries TLD server, links to Autoritiative Name Server
ANS' controlled by registrar
Resolving Queries ANS, which provides IP.
Resolving replies to OS
which replies to Browser
Browser then loads web page

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The purpose of DNS is to translate a web address into an IP address. When the user inputs the address into the browser, first the OS and browser check the Resolving Name Server to see if the IP is stored in memory. If not, the Root Name Server, Top Level Domain name server, and Authoritative Name Server will be queried, until the ANS responds with an IP. The Resolving Name Server updates it's cache with this information and then returns it to the OS. The browser will then access the page stored at that IP.

Advantages:

• No need to memories numbers/makes the web more user friendly
• Easier for search engines

Disadvantages:

• Breakdown of DNS would destroy the WWW
• Defeats the purpose of the internet being a decentralised system