At 4/4/01 10:14 AM, [EMAIL PROTECTED] wrote:
>I think you're confusing primary/secondary with master/slave.
>Primary/secondary servers are visible right in whois.
.... but are meaningless terms, because the underlying resolver knows
nothing about the WHOIS info. The terms "primary" and "secondary" are
misleading and should really no longer be used.
This question/misunderstanding comes up all the time, so here's a more
detailed answer for the record:
When a name is looked up, DNS resolvers simply ask for a list of
nameservers, all of which are considered equal. They DON'T get any
information that says "this one is primary and this one is secondary".
Even more strangely, the DNS resolver then tries the nameservers AT
RANDOM until it gets a response.
(It's actually slightly more complicated than this -- "faster" DNS
servers are tracked and subsequently get more requests. But the first
request is always random, and there's no reason why the "secondary" won't
get more requests if it's "faster".)
This means that the "secondary" server, all things being equal, gets just
as many requests as the "primary" server. There is no difference between
them for the purposes of name lookup.
The only context in which a difference between your two servers matters
is when you're talking about master and slave relationships for zone
transfers, so the terms "master" and "slave" are useful when setting up
your own DNS servers and discussing how zones are transferred from one to
the other.
They aren't useful terms if you're discussing how names are resolved to
IP addresses, though, and the terms "primary" and "secondary" are always
useless and misleading. It's better to think of them as two equal
nameservers, which for legacy reasons are marked "Primary" and
"Secondary" on forms because people are familiar with the meaningless
terms.
For more info, see these pages from the guy who literally wrote the book
on DNS & BIND:
http://www.acmebw.com/askmrdns/archive.php?question=3
http://www.acmebw.com/askmrdns/archive.php?question=304
Hope this helps.
--
Robert L Mathews, Tiger Technologies
