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CNAME lookup

Find all canonical names for a domain name with this online DNS CNAME checker. For example, try www.github.com or www.reddit.com to view their CNAME records.

How to lookup CNAME records

CNAME records can be configured by the owner of a domain name. They can be used to configure the same DNS records for two domain names without storing the information twice. When a domain name has a CNAME record pointing to another domain, that other domain name is said to be the canonical name for the domain with the CNAME record.

Example output of a CNAME lookup query

How to lookup CNAME records on Windows

To check the CNAME records for a certain domain name on Windows, follow these steps:

  1. Open a command prompt by navigating to Start → 'Type here to search' → 'cmd' → Open. Open a command prompt in Windows
  2. Type nslookup -q=cname example.com and hit [enter] to get the CNAME records for example.com. CNAME lookup in Windows
  3. The CNAME records are listed below the Non-authoritative answer heading.

How to lookup CNAME records on Mac OS

To check the CNAME records for a certain domain name on a Mac, follow these steps:

  1. Open a terminal by entering [command] + [space] → 'terminal.app' → [enter]. Open a terminal on a Mac
  2. Type dig example.com cname and hit [enter] to get the CNAME records for example.com. CNAME lookup on a Mac
  3. The CNAME records are listed below the ANSWER SECTION heading.

How to lookup CNAME records on Linux

To check the CNAME records for a certain domain name on Linux, follow these steps:

  1. Open a terminal by entering [Super] → 'terminal' → [enter]. Open a terminal in Linux
  2. Type dig example.com cname and hit [enter] to get the CNAME records for example.com. CNAME lookup in Linux
  3. The CNAME records are listed below the ANSWER SECTION heading.

How to find CNAME records

To check the CNAME records of a domain, follow these steps:

  1. Open the CNAME lookup tool. Open the CNAME lookup tool
  2. Enter the domain name and hit [enter]. Example DNS CNAME records
  3. The tool will query the CNAME records and shown them at the top of the page.

What are CNAME records and how do they work?

The DNS CNAME record can be configured to delegate the configuration of DNS records to some other DNS zone. In other words, it tells DNS clients (like web browsers) to query the DNS records of a different domain, and treat them as if they were for the domain with the CNAME record.

The most common use case for this is when you want to configure a custom domain name for a third party service. In this case you control your domain name, but the third party service controls the servers that host it. It would be inconvenient if you'd have to change your DNS settings whenever this service changes its IP addresses. This is why they commonly request you to create a CNAME record instead. That way you remain in control of your domain name, but they can change the DNS configuration of their service at any time. When such a record exists for a domain name or subdomain, the content of the record is said to be the canonical name of that domain.

Restrictions on CNAME records

There are a couple of restrictions on the configuration of CNAME records:

  • At most one CNAME record may exist for any domain or subdomain. See section 10.1 of RFC 2181.
  • The content of a CNAME record must be a valid domain name. It cannot be an ip address. See section 3.6 of RFC 1034.
  • If a CNAME record is present, no other records may be present, except for DNSSEC records (RRSIG, DNSKEY, DS, NSEC and NSEC3PARAM). See section 10.1 of RFC 2181.
  • Root domains should not have a CNAME record. Because of the previous restriction, the root domain could no longer have NS or SOA records.
  • MX and NS records must not point to a domain name that has a CNAME record. See section 10.3 of RFC 2181.

Learn more about CNAME records.

How to lookup other record types

There are other types of DNS records than just CNAME. The most commonly used DNS record types are A, AAAA, CNAME, NS, TXT, MX and SOA. If you'd like to look up all records of these record types, you can do so with nslookup. Click any of the record types below to find DNS records for that specific record type.