25 Apr
2005
25 Apr
'05
7:11 p.m.
My theory is as follows. The query causes the caching NS to get the two answers but the software stores them in numerical order. The default for bind is to "round-robin" so it choses the first (and thus the lower IP address) as the first value. Since the TTL is zero, the software then discards the data so it never gets to select the second value in its robin robin scheme.
Does this sound plausible?
It's plausible. I would assume this behavior without looking at the source code, too.
Has anyone else observed this? Is it a bug or a feature?
It's a feature. Anything which discourages the use of TTL 0 is a feature.