Domain Names and the Domain name system.
According to Wikipedia “a domain name is a string that identifies a realm of administrative autonomy, authority or control”, in simpler terms it is just a line of units that is used to identify a part of the world wide web that someone has control over, this means someone who owns the domain name for one thing can not have it used by another person.
A domain name is also a way for a human to remember how to get to a website or particular point on the internet, which a computer and the internet can also interpret as well. On the internet computers and hardware identify each other via the use of Ip addresses. Ip address come in the form of V4 and V6, IPV4 is made up of binary while IPV6 is made up of hexadecimal.
IP addresses are very difficult for humans to remember, so we need an easier way to access websites. This is done through domain names. An example of an IPV4 address would be 20.250.100.175. An example of a domain name instead would be www.google.com, this is significantly easier to remember then the Ip address for a sight.
A computer though can not recognize what the Ip address of a domain name is, due to this they need to go through the domain name system to translate the URL (Uniform Resource Locator)’s domain name into a Ip address.
The first step is that the web browser checks the local cache on the computer to see if this has already previously been searched or not, if it has not been before, the DNS resolver will ask the root name server if it recognizes the domain name, in this example we are going to use www.fasthosts.com. The root name server will not be able to recognize this but will recognize the .com, the root name server will then point the resolver where the .com server is. This server will be the Top layer domain server (TLD server), the TLD server will be able to recognize fasthosts.com but not www.fasthosts.com. The TLD server will then tell the resolver at which server the domain is stored. The resolver will then look to the authoritative name server which finds the final domain name of www.fasthosts.com and its corresponding Ip address. The Ip address is then sent back to the web browser which then sends a request to the web server with the website on it and the result is sent back.
Records
There are two different types of records, A records and MX records. These records are used to save the IP addresses of domain names to the cache of the computer, they are given a set time to live (TTL), A records store the IP for websites while MX store the addresses for emails.
CDN
CDN is a type of record similar to cache that is not stored locally on the computer this is between the network provider and the tier 1 network provider.
Other
Different registrars (organizations) look after individual domains.
ICANN managers and looks after the root servers.
DNS is completely un-encrypted despite a secure version DNSSEC existing.