On 24/03/12 07:41, Andrei Popescu wrote:
On Sb, 17 mar 12, 21:33:30, Scott Ferguson wrote:
I just thought it strange that he should be getting served a different
IP address to what I get. Possibly that's his ISP's DNS cache.
No, it's probably just Round-robin DNS
http://en.wikipedia.org/wiki/Round_robin_dns
It's very unlikely to be the cause of the problem. (and yes, round-robin
is used there).
The 3 addresses being served at the time of Bret's problem didn't
include the one he was getting the *404 error* from. If his problem
wasn't DNS based he'd just get a different address on the next attempt -
he kept getting the same address. Not one of the addresses I was getting
at the same time, using the same root DNS he 'should' have been sourcing
(thought probably indirectly depending on his setup and ISP).
I got 404s from that address at that time also - perhaps that's why the
DNS weren't handing out that address then. (caching is one of the
problems with using round robin DNS for public resources)
It would appear probable that his problem, now resolved, was more to do
with how DNS caching was being handled by his Smoothwall. I can't rule
out peering arrangements with his ISP, or their DNS caching, but I note
that Bret is replacing his Smoothwall setup.
Kind regards,
Andrei
Kind regards