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This article provides an explanation of DNS glue records.
What Are DNS Glue Records?
DNS glue records associate authoritative nameservers with their IP addresses, allowing DNS resolvers to locate those nameservers without encountering circular DNS lookup dependencies.
The official guidelines for glue records are outlined in RFC 9471.
Glue records are especially important when a domain uses nameservers belonging to the same domain. They provide the information needed to locate authoritative DNS servers before those servers can answer DNS queries.
Understanding Glue Records
Suppose the domain raddemo.host uses the following authoritative nameservers:
| Nameserver | IP Address |
|---|---|
| ns1.raddemo.host | 192.0.2.10 |
| ns2.raddemo.host | 192.0.2.20 |
These are example IP addresses reserved for documentation. Replace them with actual nameserver addresses when configuring your domain.
Because these nameservers belong to raddemo.host, DNS resolvers need a way to discover their IP addresses before they can query them.
Glue records provide those addresses through the parent DNS zone.
How Do Glue Records Work?
When a visitor attempts to access a website, a DNS resolver follows a delegation process to discover the domain's authoritative nameservers.
Requests DNS information for raddemo.host.
Return the delegated nameservers and the necessary glue IP addresses.
The resolver contacts the authoritative nameserver using the supplied IP address.
What Happens Without Glue Records?
If the domain uses nameservers within its own domain but lacks the necessary glue records, a circular dependency can occur:
- A DNS resolver attempts to locate
raddemo.host. - The .HOST registry directs the resolver to
ns1.raddemo.host. - The resolver needs the IP address of
ns1.raddemo.host. - Discovering that IP address requires contacting the very nameserver the resolver is trying to locate.
When Are Glue Records Required?
Whether glue records are necessary depends on the hostnames used for the domain's authoritative nameservers.
Example 1: Using Custom Nameservers
Suppose you want to operate private nameservers for raddemo.host.
Domain: raddemo.host Nameserver 1: ns1.raddemo.host Nameserver 2: ns2.raddemo.host
Because both nameservers belong to the domain being delegated, glue records are required to make these nameservers reachable through normal DNS resolution.
Example 2: Using Your Hosting Provider's Nameservers
Now consider a domain using nameservers operated by its hosting provider.
Domain: raddemo.host Nameserver 1: ns1.serverprovider.net Nameserver 2: ns2.serverprovider.net
In this configuration, the nameservers belong to serverprovider.net, not raddemo.host.
Therefore, the owner of raddemo.host does not need to register glue records for these nameservers.
The operator of serverprovider.net is responsible for maintaining any required glue records for its nameserver infrastructure.
ns1.serverprovider.net, you generally only need to update your domain's nameserver settings at the registrar.Glue Records vs. Regular DNS Records
Although glue records and normal DNS address records can contain identical IP addresses, they serve different purposes.
| Feature | Glue Record | A/AAAA Record |
|---|---|---|
| Purpose | Locate authoritative nameservers | Resolve hostnames to IP addresses |
| Stored At | Parent DNS zone | Authoritative DNS zone |
| Managed Through | Registrar or registry | DNS management interface |
| Example | ns1.raddemo.host → 192.0.2.10 | ns1.raddemo.host → 192.0.2.10 |
| Primary Use | Nameserver delegation | Hostname address resolution |
A glue record does not replace the normal authoritative DNS A or AAAA record for a nameserver hostname.
Both should reference the correct IP addresses to maintain consistent DNS operation.
How to Register Glue Records
If you intend to use custom nameservers such as ns1.raddemo.host, follow these steps.
- Sign in to the control panel provided by your domain registrar.
- Navigate to the domain management section and select the domain you want to configure.
- Locate the option labeled Register Nameservers, Child Nameservers, Host Records, or similar.
- Register
ns1.raddemo.hostusing its assigned IPv4 address. - Repeat the process for
ns2.raddemo.host. - Add IPv6 addresses if your nameservers support IPv6.
- Update the domain's nameserver delegation to use the newly registered nameservers.
- Confirm that matching A and/or AAAA records are configured on the authoritative DNS servers.
Main article: How to Add Glue Records for Various Registrars
How to Verify Glue Records
DNS glue records can be inspected using the dig utility, which is available on Linux, macOS, and systems with DNS diagnostic tools installed.
Step 1: Trace the Domain's DNS Delegation
dig +trace raddemo.host NS
This command follows the DNS delegation chain from the root nameservers toward the authoritative DNS servers.
Step 2: Identify the .HOST Registry Nameservers
dig +short NS host.
This retrieves the authoritative nameservers responsible for the .host top-level domain.
Step 3: Query the Parent Registry
Select one of the returned .HOST registry nameservers and query it directly.
dig @<host-tld-nameserver> raddemo.host NS +norecurse
Replace <host-tld-nameserver> with an actual nameserver returned by the previous command.
Review the DNS response. The AUTHORITY SECTION generally contains the delegated nameservers.
When applicable, the ADDITIONAL SECTION includes the glue A or AAAA records needed to contact those nameservers.
Step 4: Check Provider-Managed Nameservers
If your domain uses nameservers under serverprovider.net, you can confirm their publicly resolvable addresses using:
dig ns1.serverprovider.net A dig ns1.serverprovider.net AAAA
These commands test normal DNS address resolution. They do not independently confirm whether glue records exist.
To inspect the parent delegation for serverprovider.net, query a .NET registry nameserver directly:
dig @a.gtld-servers.net serverprovider.net NS +norecurse
Examine the response for the nameserver delegation and any accompanying glue records.
Frequently Asked Questions
Do I need glue records if I use my hosting provider's nameservers?
Generally, no. If your domain uses provider-managed nameservers such as ns1.serverprovider.net, you only need to configure the correct nameservers at your registrar. The provider manages any required glue records for its infrastructure.
Are glue records the same as DNS A records?
No. Although both can associate hostnames with IPv4 addresses, glue records are supplied through the parent DNS zone to help resolvers locate authoritative nameservers. Regular A records are served by the authoritative DNS zone.
Can I configure glue records through cPanel or WHM?
Typically, no. cPanel and WHM allow administrators to configure DNS records and nameserver settings, but glue registration is normally performed through the domain registrar or registry management interface.
What happens if my glue records contain an incorrect IP address?
DNS resolvers may attempt to contact an incorrect or unreachable nameserver. Depending on the remaining available nameservers, this can cause intermittent DNS failures or complete loss of domain resolution.
Do I need to update glue records when changing nameserver IP addresses?
Yes. When a nameserver's IP address changes, any corresponding glue records must be updated through the registrar. Matching authoritative A and AAAA records should also be updated.
Are glue records needed for IPv6?
IPv6 glue records can be registered using AAAA records at the parent zone when IPv6 nameserver addresses are needed for delegation.
How long do glue record updates take?
Registry updates may become visible relatively quickly, but cached DNS delegation information may remain until its TTL expires. Depending on the registrar, registry, and resolver caching, updates can take several hours or longer to appear consistently.
Summary
Glue records are an important part of DNS infrastructure when a domain uses nameservers hosted within that same domain.
For most hosting customers using provider-managed nameservers such as ns1.serverprovider.net, there is no need to create or maintain glue records manually.
However, customers who wish to use custom nameservers such as ns1.raddemo.host must register the appropriate nameserver host records through their domain registrar.
