zero SOA TTL - still best practice?

[Karl Auer]

On Thu, 2010-08-26 at 11:23 -0400, Josh Littlefield wrote:
> Confirming, RFC 2308 makes it clear that the negative caching of all
> records for a zone is limited to the minimum of the SOA TTL and the SOA
> "minimum" TTL field (which was given this new negative caching TTL role
> in RFC 2308).

It's not clear to me why the lesser of the two is taken, or indeed why
they have a relationship at all. What is the rationale there? Why not
just use the minimum TTL as the negative cache TTL?

Having read the history in RFC2308, I suspect it is because the minimum
TTL has had a few meanings over time, and was often set far too high, so
the SOA TTL is being used to "sanity check" it, as even a feral zone
administrator will not want too high a value in the SOA TTL.

Regards, K.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)                   +61-2-64957160 (h)
http://www.biplane.com.au/kauer/                   +61-428-957160 (mob)

GPG fingerprint: B386 7819 B227 2961 8301 C5A9 2EBC 754B CD97 0156
Old fingerprint: 07F3 1DF9 9D45 8BCD 7DD5 00CE 4A44 6A03 F43A 7DEF
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part
URL: <https://lists.isc.org/pipermail/bind-users/attachments/20100827/217131a5/attachment.bin>