Why when DNS is down is not possible to Telnet a Unix server 1

[CELE1]

This is the scenario:
We have and HP UX n windows servers (NT 4.0 and 2k). In our network environment one of the Windows servers is acting as the DNS and WINS for the entire network.

We have experienced some times this:
when this server (DNS)goes down it's not possible to Telnet to Unix servers, we can ping but no access them.

Can some body explain why is this happening ? why the access to the UNIX servers depends of the DNS ?

TX

CELE1

 

[jimbopalmer]

You cannot ping or telnet by IP Number?

the names will not work without a naming service, but the IP number still should work.

DNS Domain Name Service - the TCP/IP standard
WINS Windows Internet Name Service - Microsoft only I tried to remain child-like, all I acheived was childish.

 

[CELE1]

Sorry I missed this part:
We can ping by IP but not by name.
Can not telnet by name neihter IP.
My concern is why even we don't need name resolution the Unix servers depend on that DNS server.

Thanks

CELE1

 

[SupaTech1]

Does the server that hosts you DNS provide router to the internet or the network you are tring to reach. maybe you have more than one service dropping on that box.

 

[martook]

This sounds like the usual unix-server-trying-to-do-a-reversed-lookup-of-your-IP problem

To find out, just telnet to the box the next time the DNS dies, and then wait for quite some time. If you get connected after while - that's probarbly it. The timeout for reversed lookup changes between systems, so I can't tell how long you have to wait, but say around a minute or so... what you can do to solve the problem is to set a static hostname on the UNIX-server for the IP you try to telnet from.

If you ge a connection time out, you might have to change that value in your telnet application... don't know if this is possible in the lousy one that comes with Windows, but if you use a real one, that should not be a problem.

 

[CELE1]

Hello:

I believe what marktook says is right, when the DNS server went down, we could get connected to Unix server after a while.

I was wondering if there's any way to eliminate the reverse lookup IP for the Unix server either be on the Unix server or DNS server instead of add a static entry of the server name.

Cheers

 

[RLE]

Install a second DNS server with your secondary zones and said goodbye to your problem

 

[marcusvinicius]

Please, I'd like some help from you. I understood the solution with the utilization of DNS. But I'd like to disable the reverse lookup. Does anybody know how to do it in a Unix enviroment?