DNS (Domain Name System or Service or Server):
- It is an internet service that translates domain names into IP addresses.
- Domain names are alphabetic, they are easy to remember.
- Internet is really based on IP address.
- Every time we use a domain name, therefore a DNS service must translate the name into the corresponding IP address.
- For example, the domain name of www.google.com may translate to 216.58.220.36.
- The DNS is a hierarchical decentralized naming system for computer, services or any resources connected to the internet or a private network.
- It associates various information with domain names assigned to each of the participating entities.
- There are two DNS servers primary DNS and secondary DNS.
| Primary DNS | Secondary DNS |
|---|---|
| It is a master server. | Secondary DNS is referred as slave server. |
| A primary DNS server is responsible for reading data related to domain zone. | Secondary DNS is responsible for obtaining zone data from the primary DNS server immediately after being setup. |
| It is also responsible for communicating with the secondary server. | Each time a secondary DNS server functions is recieves information from the primary DNS server. |
| Each domain name is assigned to primary DNS server for redundancy and to specify the process of server administration. | Secondary severs are nearly as important as primary DNS server because they offer security through redundancy. |
| The process of primary DNS communicating with secondary server is known as zone transfer. | It acts as back up by storing the data from primary DNS. It acts as primary DNS during failure of primary DNS. |
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