SOA Minimum comment in "dig" output

Matus UHLAR - fantomas uhlar at
Mon Feb 12 10:02:12 UTC 2018

>> RFC 2308 "DNS NCACHE" defines the last field of the SOA RR as "the TTL of
>> negative responses".

On 12.02.18 10:29, Daniel Stirnimann wrote:
>Negative caching TTL is not defined as the last field of the SOA RR:

yes, it is, as RFC 2308 section 4 says:

     The remaining of the current meanings, of being the TTL to be used
     for negative responses, is the new defined meaning of the SOA minimum

>"When the authoritative server creates this record its TTL
>is taken from the minimum of the SOA.MINIMUM field and SOA's TTL."

this is the TTL of the SOA returned in NXDOMAIN response.

a bit schizophrenic, but the SOA "minimum" field clearly applies there,
unless your SOA TTL is shorter.

>> Why is dig still showing the old description "minimum" about the meaning
>> of the field?

apparently nobody changed that comment in 'dig' source code yet.

>Because minimum is what it is? It's not negative caching ttl, see above.

while called "minimum", as the OP correctly noted, it's defined as TTL for
negative responses. describing it as "negative TTL" would be correct.

Matus UHLAR - fantomas, uhlar at ;
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