BIND statement fetches-per-zone

Name

fetches-per-zone

Syntax

fetches-per-zone <integer> [ ( drop | fail ) ];

Blocks

options {
	fetches-per-zone <integer>;
...
};
...
view "<name>" {
	fetches-per-zone <integer>;
...
};

Default value(s)

If the statement is not used its default value is 0, meaning that the feature is disabled and no queries are dropped.
If the statement is used but neither drop nor fail are specified, drop is assumed.

Introduced

• Date: 2015-08-06
• Version: 9.10.3b1

Deprecated

Still current as of 2025-03-19.

Description

This statement limits the number of simultaneous queries permitted to any one domain before named blocks new queries for data in or beneath that domin. The value should reflect how many fetches would normally be sent to any one domain in the time it would take to resolve them and should be smaller than recursive-clients.

When many clients query for the same name and type simultaneously these clients are all attached to the same fetch, up to the max-clients-per-query limit, and only one upstream query (fetch) is sent. However, when clients are querying for different combinations of QNAME and QTYPE, multiple fetches are sent and max-clients-per-query is not effective as a limit.

The chosen value may optionally be followed by one of the keywords drop or fail, indicating whether queries that exceed the fetch quota for a domain are dropped with no response, or responded to with SERVFAIL.

The current list of active fetches can be dumped by running rndc recursing. The file this produces contains the number of active fetches for each domain and the number of queries that have been passed (allowed) or dropped (spilled) as a result of the fetches-per-zone limit.