AIX System Name Resolution Problem

[richard2000]

We have an RS/6000 box running AIX 4.3.3 that, for reasons unknown, has decided to stop resolving names stored in its /etc/hosts file. If we choose to ping, for example, 192.168.10.10, no problem. But if we execute ping hostname , we get no response from the machine. We've verified the presence of the hosts file in the /etc/ directory and have checked its permissions (they're ok). Logins have slowed to a crawl (long delay between "connecting" and login prompt), as well, and print jobs to JetDirect print servers (listed in the hosts file) are, understandably, slow (but eventually surface).

As far as we can tell, there's been no unauthorized access to the machine and -- in the period between "working" and "not working" -- we've done absolutely nothing to the system.

Any ideas?

Thanks,

Richard

 

[Morsing]

Your description is a bit confusing. If you ping a host, the client (the one you're pinging from) needs to be able to resolve the name. This should be done by the name server.
If login sessions to the host are slow, it's because it can't lookup the client, most likely because your name server is down and not because of the hosts file on the server.

In short: check your name server. Henrik Morsing
IBM Certified 4.3 Systems Administration

 

[BobMCT]

Check for the existence and contect of the following two files:

/etc/resolv.conf
/etc/netsvc.conf

The contect of both should have "resolve=hosts,bind"

Which instruct the system to search the hosts file before using DNS. Of course one assumes your hosts file is complete and correct.

Just my $.02 / sometimes its the simple stuff that works.

 

[aixserf]

Hello,
It sounds like a nameserver issue. Try to ping the name server(s) listed in the /etc/resolv.conf file. This problem usually appears when your nameserver or Internet connection goes down. Renaming the the resolv.conf file can be a quick fix until the problem is resolved.
In AIX 4.3.3 and version 4.3.3.15 of bos.net.tcp.client a new option is available for the telnet line in /etc/inetd.conf. If the -c option is added the reverse lookup of telnet will be suppressed.
(partial section of /etc/inetd.conf)
telnet /usr/sbin/telnetd telnetd -a -c

 

[richard2000]

Thanks to everyone for all of the input, but I suppose I should mention something that I did not in my first post: This machine NEVER had a name server configured. The only names that the machine ever had to resolve itself were its print servers (less than 1 dozen) and the machine that it replaced a while back, so we simply chose to maintain a simple hosts file for that.

Suddenly (last week) the machine decided that it would no longer look up names in /etc/hosts. The slow login problem (logging in to this machine) occurred at the same time.

We did try BobnMFDC's suggestion (neither of these conf files existed or had non-remarked commands), but do have one question: Does the machine or its enet interface need to be restarted for the change to take effect?

We're still at square one. Thanks,

Richard

 

[DSMARWAY]

Hi,

Are ther any processes running on your server clocking up a lot of time ( simple check ps aux | head -10 | more )

Are there any errors in the error report , errpt -a | more) ?

Check network details i.e. run entstat -d en?
check for collisions , bad packets etc..

IS your console easily accessible , if so do the same symptoms happen on your console ?


One other possibility could be your inetd daemon , could have gone loopy , try refreshing it ( refresh -s inetd )

HTH

 

[aixserf]

Hello,
Just a shot in the dark. You may want to make sure no one started the DNS server on AIX. If you type in domainname at a shell prompt you should get back no response. The default response if DNS is setup will be rs6000.
You can go into smit yp --> configure modify NIS -->Remove NIS. Plese verify you are not using other NIS services before you run this step.
If this is not the case,then check performance with steps suggested by DSMARWAY.