The Anatomy of a DNS Zone File – Part Two: What are NS Records and Why Are They Important to DNS?

What-are-NS-Records-Important-DNS

An NS record or (name server record) tells recursive name servers which name servers are authoritative for a zone.  Recursive name servers look at the NS records to work out who to ask next when resolving a name.

You can have as many NS records as you would like in your zone file.   The benefit of having multiple NS records is the redundancy of your DNS service.  It is important to note that in order to get the most redundancy out of your NS records, they should be hosted on different network segments.  If they are not hosted on different networks segments and the network goes down, your DNS goes down with it. Check out No-IP Plus Managed DNS if you are interested in redundancy and reliability for your domain.

NS records help to ensure that all of the domains on your server are available at all times. Multiple NS records ensure that your customers are able to reach your site each and every time without any problems, even if one or more of your nameservers are unreachable. (Again only if they are hosted on different network segments.)

An example of this is if your business is located in an area that is hit by a natural disaster and your web servers at that location are down, your NS records will point to an additional name server that is hosted elsewhere (where mother nature has not wreaked havoc) and the customers are still able to reach your site and will never suspect anything is awry.

Another great example is if your website is attacked by a DDoS (Distributed Denial of Service) attack your entire website will not be down. Traffic will be routed to the other name server location that has the backup of the primary name server.

Please see the following example of the NS records for No-IP.com
no-ip.com. 73002 IN NS ns1.no-ip.com.
no-ip.com. 73002 IN NS ns2.no-ip.com.
no-ip.com. 73002 IN NS ns3.no-ip.com.
no-ip.com. 73002 IN NS ns4.no-ip.com.
no-ip.com. 73002 IN NS ns5.no-ip.com.
no-ip.com. 73002 IN NS ns1.no-ip.com.

Check out Part 1 and Part 3 of this series:

The Anatomy of a DNS Zone File: SOA Record

Anatomy of a DNS Zone File Part Three: MX Records

 

Questions or Comments? Please leave them below.

 

8 Comments.
  1. Nice explanation.
    However, I am confused:
    “…your web servers at that location are down,…” you claim “…the customers are still able to reach your site…”
    How can that be, only if you have redundant web servers, I cannot see how many NS can rectify that problem.
    I am in doubt that you know what you are talking about, it might just be that the text I unclear to me.
    Regards
    Carl

  2. It’s hard to seek out knowledgeable individuals on this subject, however you sound like you already know what you’re talking about! Thanks

  3. Craig

    NS records help to ensure that all of the domains on your server are available if your website happens to be down. NS records ensure that your customers are able to reach your site each and every time without any problems. (Again only if they are hosted on different network segments.)

    Is this paragraph correct because I would like to know how having dispersed servers allows my website to be available. I was under the impression that my website could only sit on the one server with one DNS ‘A’ record pointing to that server’s IP. How do I set up DNS entries to allow the hosting of my website on multiple servers ??

    • Thank you for your comment. We have corrected the post to be a little more clear. Please let me know if you have any additional questions or further confusion.

  4. Hi Natalie,

    It appears, even after your correction, the information is still inaccurate. Having redundant name servers is good practice because should one of the **name server** becomes unavailable, the others will still be able to point to your **web server**.

    If you **web server** is down, no matter how many NS records you have, the client won’t be able to reach the site. The best that can happen is that a cached version of the site is up.

  5. ¿How can i create NS host in NOIP service?

    I have NOIP PLUS

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