What are Glue Records?

What is it?

Glue Records, or Nameserver Glue, relate a nameserver on the internet to an IP address. This relationship is set up at the domain registrar for the main domain on which the nameservers were created.

Names into IPs? That sounds a lot like normal DNS! How is Nameserver Glue different?

Let’s take a wider look at how DNS works. Your computer normally has no idea how to find a website on the internet from a name that you type in (like liquidweb.com), just the same as if I said “Call The Getty”, you wouldn’t know how to contact them. This first has to be turned into an IP address (like, just the same as needing to know the phone number of The Getty in order to reach them.

We normally leave this translation of names to IPs to DNS nameservers, which are like the white pages of the internet. But, even though you may be able to discover the nameserver for a domain, that’s still a domain name (like ns1.liquidweb.com) which must be turned into an IP address before it can be accessed. In our Getty example, a similar conundrum might be “Oh, you don’t know the number for The Getty? Just call the LA Visitor Bureau’s Office,” without knowing their number either. In order to look up that ns1.liquidweb.com A record, you will need to already know the IP address for liquidweb.com! Catch-22, right? That’s where Nameserver Glue comes to the rescue.

The authority for a domain is the domain registrar. The registrar holds a list of the nameservers for a particular domain name, and similarly, is able to translate a nameserver name into an IP so that you can contact the nameserver to get DNS records for a domain it controls.

Can you run through an example?

Of course! Let’s use liquidweb.com again. We start out on our browser, not knowing anything about the domain’s IP, or even what nameservers it uses. Our first step is our local DNS cache and hosts file, to see if we have visited the domain before and have a cached local record. In this example, we haven’t. Next, we check the nameservers at our ISP (Internet Service Provider) or another local caching nameserver, to see if they have a cached record. Let’s say they don’t, and we have to start from the root. We use a public service to determine the registrar, and subsequently, the nameserver names. You can do the same thing by using the linux whois command:

whois liquidweb.com

This tells us the domain registrar (network solutions) and the authoritative nameservers (ns.liquidweb.com and ns1.liquidweb.com).

Now we have the nameservers for liquidweb.com, and we know who to contact to get the IP address for the domain. But we still can’t contact those nameservers; we only know the name, and we can’t do another DNS lookup for them, since the records are on the nameservers themselves! So, we ask the registrar for the IP addresses of the nameservers as well. You can test this query using the whois tool as well:

whois ns.liquidweb.com

In our example, we get and as the nameserver IPs.

Now that we have IP addresses, we can ask ns.liquidweb.com and ns1.liquidweb.com about the IP address of liquidweb.com, and the browser can carry on with its query for the web page.

You can see that without Glue Records set up at the registrar, we would never be able to contact the nameservers, and no one would be able to go to liquidweb.com!

Do I need Glue Records?

Anyone who uses a shared set of nameservers, like ns.liquidweb.com and ns1.liquidweb.com or the CloudFlare service, will probably not need to worry about Glue Records, since these are already set up. But, if you are using custom nameservers, like ones based around your domain name, or you are setting up a new set of nameservers for your clients, or moving your nameservers from one set of IPs to another during a domain migration, you will need to make sure your Glue Records are set up properly.

How do I set up Glue Records for my nameservers?

Every domain registrar has different steps for setting up the nameserver Glue Records for a domain. But, you will need to know a few things for certain in order to be successful:

  • First, you will need your registrar login information for the domain on which you would like to set up nameservers (whomever you purchased your primary domain name from).
  • Next, you need to know the names of your nameservers (most people choose ns1 and ns2).
  • Finally, you need to have IP addresses for each of your nameservers. Some registrars are OK with using the same IP address for both nameservers, but sometimes they want different IPs.

For cPanel servers, and most other servers running the BIND nameserver software, all of the IPs on the machine are set up to listen for DNS requests, so you can use any of your IPs for any of your nameservers. But, you should also make sure that the actual A records for the nameservers also match whatever you enter in as Glue Records, just to keep everything properly aligned. Also, nameserver software (like BIND) and webserver software (like Apache or Nginx) listen on different network ports, so you can use the same IP for your nameservers as you do for serving websites without any issues.

If you don’t have access directly to the registrar, ask your domain name reseller to set up the Glue Records for you. If you purchased your domain name through Liquid Web, just open a support ticket or chat with us, and we can handle the rest.

Be Sociable, Share!
Here's 75 % off, Launch a New VPS Today. Find out why 30,000 customers have chosen our Best-in-Class Performance & 24x7 Heroic Support