Re: after type the password need to wait a long time when telnet solaris

From: Logan Shaw (lshaw-usenet_at_austin.rr.com)
Date: 10/29/03 

Date: Wed, 29 Oct 2003 17:10:37 GMT

[ home many nameservers in /etc/resolv.conf? ]

Darren Dunham wrote:

> Logan Shaw <lshaw-usenet@austin.rr.com> wrote:
>>However, I just did a test (using "snoop -r port 53") and it only
>>consulted the first three I had in the list.

> It actually used 3? Was something wrong with the first two?

Nothing was wrong with them other than the fact that they were
addresses (on the 10.0.0.0/8 network) of machines that don't exist.
Well, the first four were, and the last was 127.0.0.1, which
does exist and which answers DNS queries.

>>I think this is kind of a bummer. I should be able to put 4 or 5
>>of them in there if I need to. (I don't think I'll ever want to
>>put 10 in there, though...)
>
> You think you have reliability problems with three separate servers that
> would not affect a fourth or fifth?

Well, no, but I think it can make for a cleaner configuration.
Suppose my organization has two sites, both connected by a
relatively-slow WAN link. For performance and reliability
reasons, I want to have two nameservers at each site. At site
#1, I have servers A and B, and at site #2, I have servers C and D.

The natural thing is to put the list A,B,C,D in resolv.conf files
at site #1 and C,D,A,B in the files at site #2. But since I can
only put three, I have to do something more like A,B,C at site #1
and C,D,A at site #2. Now, suppose someone at site #1 remembers
that we put two locals and one remote in resolv.conf, but they forget
which remote we use. They might put A,B,D in a resolv.conf at
site #1. Now, suppose further that I decide I must change the
IP address of D. Since I believe it doesn't occur in resolv.conf
on any host at site #1, I might just not bother to update the hosts
at site #1. And then they'd be pointing at a server which doesn't
exist (or worse, at a host which does exist and which isn't
intended to be a server).

I admit this is sort of a far-fetched scenario, but the point
is that in some organizations, the natural thing to do would
be to have four nameservers, and it makes things simpler and
easier if you can just put them all in resolv.conf (in the
appropriate order, of course). Basically, I don't want to
be forced to make and remember an arbitrary decision, because
the extra complexity will increase the likelihood of error.
And Murphy's Law says the likelihood will be higher than
you think. :-)

> I agree that it seems an arbitrary
> limitation, but most of the time I see folks trying to use more than 3
> nameservers, they're trying to use them in non-identical ways, which is
> incorrect.

Agreed. That's what the "forwarders" directive in named.conf
is for. (Well, that's one thing it's for...)

   - Logan

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