Nameserver Types

There are four primary nameserver configuration types:

master: Stores original and authoritative zone records for a namespace, and answers queries about the namespace from other nameservers.

slave: Answers queries from other nameservers concerning namespaces for which it is considered an authority. However, slave nameservers get their namespace information from master nameservers.
caching-only: Offers name-to-IP resolution services, but is not authoritative for any zones. Answers for all resolutions are cached in memory for a fixed period of time, which is specified by the retrieved zone record.
forwarding: Forwards requests to a specific list of nameservers for name resolution. If none of the specified nameservers can perform the resolution, the resolution fails.

A nameserver may be one or more of these types. For example, a nameserver can be a master for some zones, a slave for others, and only offer forwarding resolutions for others.