Understanding Glue Records
We know that a domain is associated with an IP address that directs visitors to the right location in the Internet that houses your site and its contents from what we learned in our article Understanding Domains. A Glue Record works in the same way by binding the IP address to a static cache so visitors can always locate your site without issue. This avoids impossible dependencies for that DNS zone. Glue Records are at your registrar and allow traffic to be directed without using the lookup process of DNS. You often see a Glue Record used for nameservers, but it is occasionally in other records depending on circumstances.
When DNS requests an IP address for a specific domain, it’s often queried at the registrar first. The registrar will provide any information that it has for the DNS. If there is a Glue Record, this is presented as the place to look for any DNS zones.
So, what does all this mean? Let’s look at an example:
I will show the difference between having Glue Records and not having them in this example, . If you do not provide the registry with Glue Records, other nameservers trying to look up the IP address of example.com would ask the .com (TLD) nameservers for a referral, and encounter the following issue:
Browser: "Hi! I need the IP address of example.com, what is it? .com Nameserver: I don't know, but you can ask the nameserver. It was ns1.example.com the last time I checked. Browser: Okay! in order to send a query to ns1.example.com, I need the IP address. What is that? .com Nameserver: I don't know, ask the parent example.com Browser: I can't, I need an IP address.
When you set a glue record at the registry, the DNS lookup will go more like this:
browser asks for the IP address.... Browser: Thanks! In order to send a query to ns1.example.com, I need the IP address. .com Nameserver: Yes, it's 192.0.2.0 the last time I checked. Browser: Thanks! I can see it now! Sending query.
What does this mean for you?
During the migration process you will be asked what DNS you wish to use upon completion. Typically this is either external (your own nameservers like GoDaddy or an external server), custom nameservers (nameservers that are located on your WHM that we will also have access to) or our Nameservers. The migrations team can assist in setting up the nameservers for either custom or our nameservers and will give instructions on what needs to be updated as well as assisting wherever possible, but you will be responsible for changing any external information including glue records for custom domains or any DNS inside of external DNS zones. Depending on the setup, you can use the following articles to change your name servers:
If you decide to change nameservers during the process, e.g. moving your DNS location from GoDaddy to Liquid Web, the change will need to be made at the registrar. Once again, we can provide information on how to make this change and when it is best to do so during the migration process.
Not sure where your registrar is? Check out our article Where Is My DNS Hosted? for information on finding your registrar and gaining access to the DNS records to change the Glue Record.