DNS Zone Declarations and Options
While options and other named.conf parameters described below relate to the configuration and operational parameters of the DNS service, the zone declaration statements identify the zones with which the DNS service on this server is configured. Each zone statement identifies the name and type of the zone. The name corresponds to the zone name within the DNS domain tree, while type may be one of the following:
- master - this zone is the master copy of the zone information
- slave - this zone is authoritative for the given zone name, but it retrieves its copy of the zone from another DNS server, usually that configured with the copy of the zone as type master, though slaves can also retrieve copies from other slaves.
- stub - this zone contains only NS records retrieved from the master copy of this zone; clients querying a server which has a stub zone corresponding to the query will attempt to resolve all queries leveraging these NS records to identify the server to query for authoritative zone information.
- static-stub - new in BIND 9.8.0, the static-stub zone type is like a stub zone in that it contains only NS (and glue) records for the zone, but these records are configured within the server options (statically), not via zone transfer from a master server.
- forward - this zone should contain query forwarding information to steer queries for this zone to particular recursive DNS servers.
- hint - this zone contains the 'last resort' set of NS and glue records for root DNS servers. This zone provides information a recursive server needs to jump to the top of the domain tree for traversal down to the queried zone and resource record(s).
- delegation-only - this zone provides referrals to DNS servers further down the domain tree and not direct resolution. This zone type was introduced primarily for TLD zones (e.g., .com, .net, etc.).
The general format of the zone statement within the named.conf file is:
| zone zone-name [class] { | |
| type zone-type; | |
| zero or more zone option statements; | |
| }; | |
where zone-name is the domain name of the zone, the class is the class of the zone, IN by default, zone-type is one of the possible zone types listed above, and option statements are those applicable to the particular zone type per the BIND Options Reference table .