A glue record is simply the association of a host name (name server, or DNS) with an IP address at the registry.

In order for a name server to to "work" it needs to be able to be found first. this is done by creating a glue record.

Glue records are created at the registrar of the domain name.

If your domain name is registered with Gandi, there are two different ways of creating a glue record, depending on the TLD.

The most common TLDs will allow you to create your glue record directly in your domain's control panel, in the lower left-hand corner in the Technical Settings section. Just use the link 'Create a glue record'. If you do not see that link, please contact Gandi support for assistance.

Gandi's default nameservers, which you have come to know and love by now, have the following glue records:

a.dns.gandi.net 217.70.179.40
b.dns.gandi.net 217.70.184.40
c.dns.gandi.net 217.70.182.20

In this example, the host name a.dns.gandi.net is registered at Verisign (the registry for .net) as pointing to the machine 217.70.179.40.

Therefore, when requests are made by a domain name that use a.dns.gandi.net as a name server, a.dns.gandi.net will send the request to the DNS server hosted on the machine called 217.70.179.40, which will tell it what to do.

If you try and apply DNS (name servers) to your domain on Gandi's DNS update interface and get the message (in this example let's say I want to use boom.whack-a-mole.eu):

The following error occurred while changing the DNS of your domain: boom.whack-a-mole.eu : The domain name used as DNS server does not exist.

This means that no glue records exist for nameserver boom.whack-a-mole.eu at the registry. In otherwords, you need to go to the registrar of whack-a-mole.eu (Gandi) and first create a glue record for boom.whack-a-mole.eu. Otherwise there is no way that the registry will know what server will respond to that name.

If the glue record is valid, and the DNS does not respond, then it is a server-side issue; the registrar simply tells the registry what the IP address of the host name is. In this case the administrator of the DNS server needs to verify the configuration of the server. It is useless to contact the registrar, in this case, as they do not have access to the actual server. If you are not running the DNS server yourself, you can perform a whois look-up of the IP address to see who to contact.