SOA "minimum" vs "negative ttl"

[Jack Tavares]

I believe that RFC 2308 redefines the SOA "minimum" field to be
"negative ttl"

If I create a dynamically updated zone file that looks like so:

[begin]
$ORIGIN .
$TTL 500
new.com IN SOA d62.test.com. hostmaster.d62.test.com. 2013012301 10800 3600 604800 86400
new.com IN NS d62.test.com.
[end]

When a DNS update comes into to add or modify a record and bind eventually re-writes
the master file it will rearrange the SOA and add comments (which is fine) but it labels
the last field as "minimum"

[begin]
$ORIGIN .
$TTL 500 ; 8 minutes 20 seconds
new.com IN SOA d62.test.com. hostmaster.d62.test.com. (
2013012302 ; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
86400 ; minimum (1 day)
)
NS d62.test.com.
$ORIGIN new.com.
a A 1.2.3.4
[end]

Is there a reason for this or is it just a hold over?
It is perpetrating a misconception that this is the minimum TTL.

Thanks

--
Jack Tavares

[Evan Hunt]

On Thu, Jan 24, 2013 at 01:05:33AM +0000, Jack Tavares wrote:
> When a DNS update comes into to add or modify a record and bind
> eventually re-writes the master file it will rearrange the SOA and add
> comments (which is fine) but it labels

> [...]

> Is there a reason for this or is it just a hold over?

Some of both, I think. RFC 2308 changed the semantics of the field, but
not its name; it's still called "SOA minimum" even though it represents
something else, and it's referenced that way in subsequent RFCs such as
4034.

Also, IMHO, there's a pretty good chance that if we changed the comment
from "minimum" to "ncache ttl", it'll turn out someone had a script that
depended on the existing format. I don't mind breaking people's scripts
if there's a compelling reason, but I'm not sure the benefit here is all
that significant, so inertia wins this round. :)

--
Evan Hunt -- ea...@isc.org
Internet Systems Consortium, Inc.