On Aug 4, 7:01*pm, "Clive George" wrote:
> If my DNS servers (windows boxes) go down, my AIX box really starts
> suffering. Things start taking ages.
>
> Similarly my IHS/apache web servers take ages to start at the moment, even
> with apparently working DNS (*) - if I set NSORDER=local, they start
> quickly.
>
> (* I say apparently working - I know my DNS servers don't know about my AIX
> box, but I do have appropriate entries in /etc/hosts. Well, I hope I do....)
>
> I see plenty of references to this sort of thing around the place, and the
> answer given is always "Sort out your DNS".
>
> Can anybody tell me more detail on this? Eg when it's waiting, what is it
> waiting for?
>
> cheers,
> clive

Well what happens is any time hostnames are used they have to be
translated into an actually tcpip address.
For example if you were to try and telnet to a host thats not in your
local hosts file or dns it trys to send those request out for someone
to resolve it.

So in your case if Apache is using hostnames to start services or
communicate with other servers you my get about a minute and 1/2 delay
until it gives up trying to resolve. You can sometimes see this if
you telnet to a system and it can not resolve the incoming up ip
address it will to appear to hang for about 11/2 minutes until the dns
lookup fails. You can change the delay so its shorter but best thing
to do is have local entries for at least your critical ips in your
local host table i.e the servers own ip address and any critcal
servers it talks to locally on the network. Then Have your DNS
windows people give you a list of dns servers and add them to your /
etc/resolv.conf file so it can do a search order so if 1 DNS servers
not available it will roll down to the next one.

So in short -
1. edit you /etc/netsvc.conf file put line hosts=local,bind4
which says search the local host file first if not matches then go to
DNS servers - listed in your /etc/resolv.conf

2.You can see what dns server your talking to for example try taking
out a known host from your /etc/hosts files then do a nslookup
"hostname" where hostname is the name of the server and it will show
what server is resolving it. Like wise you can also check to see if a
ip address resolves by typing host "ipaddress"

Hope this helps a little.
-Mp

"Clive George" wrote in message
news:gc2dnR5_C6UqKQrVnZ2dnUVZ8hidnZ2d@posted.plusn et...
> If my DNS servers (windows boxes) go down, my AIX box really starts
> suffering. Things start taking ages.
>
> Similarly my IHS/apache web servers take ages to start at the moment, even
> with apparently working DNS (*) - if I set NSORDER=local, they start
> quickly.
>
> (* I say apparently working - I know my DNS servers don't know about my
> AIX box, but I do have appropriate entries in /etc/hosts. Well, I hope I
> do...)

For the record, it turns out it was IPv6 breaking things - apache was trying
to do a lookup on ipv6 for the Listen directive, and our setup doesn't
really support that. Change the Listen 80 to Listen 0.0.0.0:80 and it all
starts working fine.

Now to see what happens when I pull the DNS from under the machine's feet
(ie if it copes)...

cheers,
clive