What Are Glue Records?

Table of Contents

• The “chicken and egg” problem
• How glue records work: the role of the parent zone
• Managing glue records
• Have more questions?

Glue records are a special type of DNS record that play an important role in the delegation of domain names, particularly when a domain’s authoritative name servers are part of that same domain. They are essentially IP addresses (A or AAAA records) for name servers that solve a fundamental “chicken and egg” problem in the Domain Name System.

The “chicken and egg” problem

Let’s say you register example.com and want to use ns1.example.com and ns2.example.com as its authoritative name servers (these are often called vanity name servers). When someone tries to find example.com, their DNS resolver needs to know the IP address of ns1.example.com. But how can it find the IP address of ns1.example.com if ns1.example.com is supposed to tell it where example.com is? It creates a circular dependency.

Glue records break this loop.

How glue records work: the role of the parent zone

Glue records are not published within your domain’s DNS zone. They are published by the parent zone (typically the Top-Level Domain, or TLD registry like .COM, .ORG, etc.) and/or your domain registrar.

When you register a domain and specify name servers that are subdomains of your domain (e.g., ns1.yourdomain.com), you also provide the IP addresses for those name servers to your registrar. Your registrar communicates these IP addresses to the TLD registry. The TLD registry publishes these IP addresses as glue records alongside the NS records that delegate your domain.

The process:

1. A DNS resolver wants to find www.yourdomain.com.
2. It queries a root name server, which points it to the .COM TLD name servers.
3. The .COM TLD name servers look for NS records for yourdomain.com. They find NS records pointing to ns1.yourdomain.com and ns2.yourdomain.com.
4. Crucially, alongside these NS records, the .COM TLD name servers also provide the glue records (the A/AAAA records) for ns1.yourdomain.com and ns2.yourdomain.com directly.
5. With these IP addresses, the resolver can now directly contact ns1.yourdomain.com or ns2.yourdomain.com to get the A record for www.yourdomain.com.

This extra “glue” information ensures the resolution chain can be completed.

Common use case: vanity name servers

The most common reason for needing to understand and configure glue records is when you set up vanity name servers (also known as private name servers or custom name servers). Instead of using generic name servers provided by your DNS host (like ns1.dnsimple.com), you opt to brand them with your own domain (e.g., ns1.mycompany.com).

When setting up vanity name servers, you must define the glue records (the IP addresses of ns1.mycompany.com, ns2.mycompany.com, etc.) at your domain registrar, typically in a dedicated section for “Host Records” or “Private Name Servers.”

Relationship to other DNS records

NS Records: Glue records are inseparable from NS records when the name servers are within the delegated zone. The NS record delegates authority, and the glue record provides the necessary IP address to resolve that delegation.

A/AAAA Records: A glue record is essentially an A record (for IPv4) or an AAAA record (for IPv6) that is published at a higher level in the DNS hierarchy (the parent zone/TLD) to resolve a circular dependency.

DNSimple’s role in glue records

If DNSimple is your domain registrar, you will typically manage your glue records within your DNSimple account interface when setting up vanity name servers. If your domain is registered elsewhere, you will manage them through your third-party registrar’s control panel.

Managing glue records

For step-by-step instructions on how to set up vanity name servers for your domain, please refer to Managing Vanity Name Servers.

Have more questions?

If you have additional questions or need any assistance with your glue records or vanity name servers, just contact support, and we’ll be happy to help.