POOL Record Reference
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This article serves as a reference for the structure, implementation, and key characteristics of DNSimple’s proprietary POOL record.
POOL record format
A POOL record is a proprietary record type developed by DNSimple and is not defined by any standard RFC. It is a virtual record that is dynamically resolved by DNSimple’s name servers. POOL records are available on the Solo Pro plan and higher.
In the DNSimple record editor, a POOL record is represented by the following configurable elements:
| Element | Description |
|---|---|
| Name | The host name for the record, without the domain name. This is generally referred to as “subdomain”. |
| TTL (Refresh Rate) | The time-to-live in seconds. This is the amount of time the record is allowed to be cached by a resolver. |
| Content | One hostname in the pool (for example, a.example.com). Add one POOL record with the same name for each hostname in the pool. |
Technical implementation
When a DNS resolver queries a name with POOL records, DNSimple’s name servers randomly select one of the POOL records for that name and return its hostname to the resolver as a standard CNAME record.
From the perspective of the resolver, the domain appears to have a CNAME record. The proprietary nature of the POOL record is transparent to the rest of the internet’s DNS infrastructure.
Key characteristics
Proprietary record: The POOL record is a DNSimple-specific record type and is not supported by other DNS hosting providers.
Random selection: Each query gets one hostname, chosen at random from the POOL records with that name.
CNAME answer: The answer is a CNAME, so the resolver then looks up the chosen hostname’s IP addresses itself. When DNSimple sends the zone to secondary name servers, each POOL name is sent as a single CNAME to one of its hostnames.
Have more questions?
If you have additional questions or need any assistance with your POOL records, just contact support, and we will be happy to help. You can also read more about DNS hosting at DNSimple.