Squid configuration directive dns_packet_max

Squid configuration directive dns_packet_max

Available in: v7   v6   v5   v4   3.5   3.4   3.3   3.2

This directive is not available in the v8 version of Squid.

For older versions than v5 see the linked pages above

Configuration Details:
Option Name: dns_packet_max
Replaces:
Requires:
Default Value: EDNS disabled
Suggested Config:
Maximum number of bytes packet size to advertise via EDNS. Set to “none” to disable EDNS large packet support. For legacy reasons DNS UDP replies will default to 512 bytes which is too small for many responses. EDNS provides a means for Squid to negotiate receiving larger responses back immediately without having to failover with repeat requests. Responses larger than this limit will retain the old behaviour of failover to TCP DNS. Squid has no real fixed limit internally, but allowing packet sizes over 1500 bytes requires network jumbogram support and is usually not necessary. WARNING: The RFC also indicates that some older resolvers will reply with failure of the whole request if the extension is added. Some resolvers have already been identified which will reply with mangled EDNS response on occasion. Usually in response to many-KB jumbogram sizes being advertised by Squid. Squid will currently treat these both as an unable-to-resolve domain even if it would be resolvable without EDNS.

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