DNS stops resolving....

[Jonathan Telep]

I'm hoping someone can help me. I have a new c3750 workstation running HP-UX B.11.00 A and I can't get the thing to run DNS for more than a minute before it simply stops. I have it setup on my internal network and it can resolve internal names and ping them fine but as soon as I ask it to go out to the Internet it only works for about 2 lookups and then dies and the only way to get it to work again is to reboot the workstation and then the same thing happens again. I have tried setting up DNS to run locally on the workstation and I get the same thing. I have checked and double-checked all of the pertinent files and can find no error. HP support doesn't seem to have any clues so I'm hoping someone here does. I have an older 712/60 running 10.20B and it seems to do just fine so I'm completely confused now. Please help. Thanks.

[Steven E. Protter]

The most likely cause of this problem is connectivity issues with the DNS servers on the ourside.

A good diagnostic is to try /etc/resolv.conf with just one server in it instead of three.

You can do this one by one and might help you diagnose a bad server.

A good overall networking approach is to connect to an Internal DNS server that will resolve external names for you as well. I suspect this might not be the case here.

The DNS server you are resolving must have a current(1997) file for root servers, essentially where to go when a local DNS request fails.

Example.

Workstation 1 resolves DNS requests with server hp1

Internal stuff works great, yahoo.com doesn't resolve.

hp1 DNS server isn't correctly configured to obtain or pass DNS information from domains it does is not the master server for.

A common problem.

Other possible causes:

Internet ISP is not reliable. If its spotty or down these symptoms are possible.

Your workstation doesn't need to be runninig DNS server (BIND) to correctly resolve DNS names. /etc/resolv.conf simply tells it where to look.

Make sure you have solid ping connectivity at least to the Internal DNS servers.

SEP

[Ron Kinner]

If you log onto the c3750 can you do an
nslookup hp.com ipaddressofoutsideDNS

Does that hang too?

How about if you do

nslookup hp.com hostnameofoutsideDNS

What version of BIND are you using?

Ron

[Jim Mallett]

It likely is a DNS issue and I'm probably a bit off base here but:

I've installed 11.00 a couple of times and set up my hosts file and route table, only to find out I couldn't get outside my network after 2 or 3 minutes. Turned out that our gateway didn't support ICMP requests and my hosts would think think the gateway was down and remove it from the route table.

Next time your DNS stops working, try pinging to an external IP address and see if you can get out, or see if your default gateway is missing from your route table. If you can't get out by IP then it could be this:

I had to adjust my /etc/rc.config.d/nddconf file with the following:
TRANSPORT_NAME[0]=ip
NDD_NAME[0]=ip_ire_gw_probe
NDD_VALUE[0]=0

This stopped the system from probing for my gateway and let the record stay in my route table.

Again, it's likely a DNS issue but the timing seems eerily like what I was dealing with.

Good luck,
Jim

[Jonathan Telep]

Thank-you, Thank-you, Thank-you!!!

That fixed it and it now resolves ALL external sites forever. I can also do nslookups until my hearts content. If you don't mind my asking, what is the "nddconf" file and what does it do? I didn't see it on my other system running 10.20B and am definitely curious. I think the problem is that my default gateway, although not being removed from the routing table, is actually a CheckPoint firewall and the company who configured it is incredibly paranoid so they, more than likely, disabled ICMP requests even though they're coming from inside the network (Hell, these guys won't even let us ping the damned thing from the inside!) Anyway, it does all the routing for us so I'm guessing that's what it does.

Once again, thanks, you saved me a lot of time and lost production :-)

Jon

[Jim Mallett]

As far as ndd goes, there are more settings in that than I could ever want to know. I only found out about the gateway probe issue after our network admin started locking things down.

Your best bet is to do a: man ndd

Also, the /etc/rc.config.d/nddconf file has some good explanations in it.

ndd -h supported will give you all of the configurable parameters (get a coffee first).

I shouldn't complain about our network guy though, I've learned quite a bit from his locking things down. Between him and the ITRC I don't know where I would be.

Good luck....
Jim

[Bill Hassell]

ndd does not exist in 10.20 (it was called nettune) and the /etc/rc.config.d/nddconf file is used to set specific options on bootup (or with ndd -c). Note that there are supported and unsupported parameters.

[Suresh Patoria]

If u did the all configuration properly than i can sugest the one thing

From wherever u taken the Internet connection
ask to for DNS IP address


then that IP Address put the entry in /etc/resolv.conf file

After connecting use the nslookup utility to query to other domain

[T G Manikandan]

check this

http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000062684449

On 10.20 use nettune to tune the parameters

[W.C. Epperson]

If you need any directions on how to assign points, just ask. I've gotten a lot of help from people here, and at least some of them see the points as an incentive to contribute.