Dominic Raferd wrote:
Is there a method (regex?) for reliably identifying dynamic ip
addresses?
Short answer: No.
If you really insist on going down that rabbit hole, look up the
RDNS_DYNAMIC rule from Apache SpamAssassin. It's an aggregation of 25
provider-specific probably-dynamic rDNS patterns.
Take for instance 199-127-103-235.static.avestadns.com
- it looks dynamic to me but it says it is static.
That, right there, is why not.
There is no One True Standard, and even within the more common
conventions there are quite a few variations.
This particular example would be from a provider that has declared a
range of IPs to be static IP assignments, and which has deployed a set
of default records in a particular form so that (presumably) all of
those IPs have IP->name->IP mappings even if they don't have customer-
or service-specific rDNS names on them.
-kgd
