DNS Record Types
These records indicate which name servers are authoritative for the zone / domain. NS Records are primarily used if you want to break your domain into subdomains. Subdomains indicate you are delegating a portion of a domain name to a different group of name servers, thus creating NS records to point the name of the subdomain to different name servers.
- Name: This will be the host for your domain which is actually a computer within your domain. Your domain name is automatically appended to your name. Assuming you had a subdomain sub.example.com that you wanted to delegate to ns10.example.com. The name of the record would be ‘sub’.
- Value: The host name of the server, in this example ‘ns10.example.com.’ (including the trailing dot which stands for root). If you do not include the trailing dot your domain name will be appended to the end of the record causing incorrect results.
- TTL: The TTL (Time to Live) is the amount of time your record will stay in cache on systems requesting your record (resolving nameservers, browsers, etc.). The TTL is set in seconds, so 60 is one minute, 1800 is 30 minutes, etc..
Systems that have a static IP should usually have a TTL of 1800 or higher. Systems that have a dynamic IP should usually have a TTL of 1800 of less.
The lower the TTL the more often a client will need to query the name servers for your host’s (record’s) IP address this will result in higher query traffic for your domain name. Where as a very high TTL can cause downtime when you need to switch your IPs quickly.
Example 1 – Creation of an A record for ns.example.com pointed to an IP address. The creation of an additional NS record for example.com pointed to ns.example.com:
NS Record for example.com pointed to host ns.example.com which has a value of 192.168.1.2.
NS record details:
- Name 1 : ns.example.com. is the host which are we are making a record for. In the data entry screen we enter the name field of ns (your domain name is automatically appended to it).
- IP 1 : 192.168.1.2 is the IP address.
- TTL (time to live) 1: – The 1800 indicates how often (in seconds) that this record will exist (will be cached) in other systems.
- Name 2 : example.com. is the host which are we are making a record for. In the data entry screen we leave the name field blank (your domain name is automatically appended to it).
- Value 2: ns.example.com. is the host name of the name server which we are adding to example.com. You must include a trailing dot to keep the example.com domain name from appending to the end of ns.example.com.
- TTL (time to live) 2: – The 1800 indicates how often (in seconds) that this record will exist (will be cached) in other systems.