[DNSOP] ANAME TTL considerations [issue #30 #34]

[Matthijs Mekking <[e-mail]>]

Hi,

Another issue that is still open related to ANAME is the TTL
considerations.

The current draft says that when updating sibling address records
with target address records to reduce the TTL to match the ANAME TTL if
it is greater.

I propose a change that others have expressed as well, that is the TTL
of the sibling address records should be set to the minimum of the
target address records and its intermediate records in case of CNAME
and/or ANAME chains.

The logic is that ANAME is likely to be a more static record, while its
target address records are expected to be more dynamic. Therefor it may
make sense to set different TTLs for the different RRsets, meaning we
should not try to match the ANAME TTL and the TTL of the address records.

This means that when implementing ANAME substitution at the primary,
this will likely stretch the end-to-end TTL (from the authoritative
servers for the target address records to end-user DNS caches) to  near
twice the target address record original TTL.

The suggested change can be found here:

  https://github.com/each/draft-aname/pull/61

I will leave this pull request open for a while to solicit feedback,
counter arguments, approvals, ...


Best regards,

Matthijs