Thursday, March 1, 2012

What is a glue record?

SkyHi @ Thursday, March 01, 2012
A glue record in simplest terms is an IP address that is "glued" to a specific domain or subdomain in the registry. Glue records are most commonly needed for users that are trying to use name server addresses that are subdomains of the domain itself. To explain a little further: 

John has a domain registered named domain.com. John wants to set up his own name servers (DNS) using the addresses ns1.domain.com and ns2.domain.com. The problem with this is that because of the way that DNS works, every time someone tries to access domain.com, they will have to check with one of the subdomains (ns1.domain.com or ns2.domain.com) for the address which are both "under" the domain. Since you can't get to a subdomain before getting to the domain, and the domain is what we are looking for in the first place, we seem to be stuck. Let's personify the process for finding the correct address for a domain in the DNS lookup process:


Q: "I am trying to find domain.com. What is the IP address for the website domain.com?"
A: "I do not have the address. Check the name server for domain.com. You will find the address there."
Q: "Okay. What is the name server for domain.com?"
A: "ns1.domain.com"
Q: "Okay. What is the address for ns1.domain.com so I can check there?"
A: "I do not have the address. ns1.domain.com is a subdomain of domain.com. So check the name server for domain.com."
Q: "Okay.... What is the name server for domain.com?"
A: "ns1.domain.com"
Q: "You just said that. So you know the name of the name server but don't have the address?"
A: "Yes, only the name server has the address of the name server!"
Q: "So if only the name server knows the address for the name server, how am I supposed to get the address?!"   


The solution to this is to set up a glue record. A glue record will glue the IP address to the domain/subdomain so that the process is a bit more like:



Q: "I am trying to find domain.com. What is the IP address for the website domain.com?"
A: "I do not have the address. Check the name server for domain.com. You will find the address there."
Q: "Okay. What is the name server for domain.com?"
A: "ns1.domain.com(127.0.0.1)"   



This time the name came with an address since they were "glued" together! Now that's helpful!




This process may seem very technical but setting up a glue record in the 1&1 Control Panel is actually quite easy and may have already happened without you even knowing it. Any time a subdomain is created with "ns" at the beginning, a glue record is automatically created for this subdomain. Follow the next steps to get a better understanding:

Step 1:

Log in to the 1&1 Control Panel using your Customer ID OR domain name and your password

If you have only one package, you will land on the Administration page. If you have more than one package, select the package in question to reach its Administration page.

selectLinux.png
Step 2:

Click the Domains link from the Domains & Webspace panel.

selectDomains.png
Step 3:

Click the down arrow button next to New and select Create Subdomain.

newSubdomain1.png
Step 4:

Enter a subdomain that starts with "ns" such as ns1ns2, etc. and select the appropriate domain from the drop-down box.
Click the OK button when finished to create the subdomain.

newSubdomain2.png
Step 5:

The subdomain should be set up within the next 15 minutes or so. The glue record will be applied to the subdomain since it starts with "ns" however since the glue record is a DNS record, it may take 24-48 hours until fully updated and recognized by all servers/computers on the Internet.

You must have at least two name server addresses. Repeat this process to create another subdomain that starts with "ns" such as ns2.

If you need to change the IP address that the subdomain points to, please reference How do I edit/change a domain's IP Address (A record)?


REFERENCE
http://faq.1and1.co.uk/domains/domain_admin/dns_settings/3.html