Nigeria Internet Registration Association (NiRA)

  • banner1.png
  • banner2.jpg
  • banner3.png

AFRINIC 27 MEETING

Authoritative and Recursive DNS Servers: What’s The Difference?

It is obvious the Domain Name System (DNS) is one of the most essential parts of the Internet’s infrastructure. The Domain Name System (DNS) comprises of two parts: Authoritative and Recursive Name Servers. The authoritative nameserver and recursive nameserver are important nameservers that enable DNS run seamlessly and actually respond to domain name request.

By using DNS, you can connect to a website like nira.org.ng without having to know the website’s IP address. The Authoritative DNS system provides resources of the zone whilst the Recursive DNS holds information of the host for a given amount of time specified by that Records Time To Live (TTL) value.

Authoritative DNS nameservers are responsible for providing answers to requests made by other DNS nameservers (Recursive Servers) with the IP “mapping” of the intended website. The authoritative nameservers’ simply respond to the recursive nameservers contains important information for each domain, such as corresponding IP addresses and other necessary DNS records. Essentially authoritative nameservers are like the name mapping database, that is, it contains relationship existing between a registered domain name and it corresponding IP address.

Recursive nameservers are the intermediary that respond to domain requests. It provides answer to the request if it has cached earlier, else it proceeds to the authoritative server. The caching of the name are based on the default time to live (TTL)

At the top of the DNS tree are the root domain nameservers. Every domain has an implied/hidden “.” at the end of the name, that designates the DNS root nameservers at the top of the hierarchy. Root domain nameservers know the IP addresses of the authoritative nameservers that handle DNS queries for the Top Level Domains (TLD) like “.ng”. It first asks the root domain nameservers for the IP address of the TLD server, in this case, “.ng.” (working on www.nira.org.ng).

Afterwards it asks the authoritative server for “org.ng”, where it can find the “nira.org.ng” domain’s authoritative server. Then “nira.org.ng” is asked where to find “www.nira.org.ng”. Once the IP address is known for the website the recursive DNS server responds to your computer with the appropriate IP address.