12.04.3 - Reverse DNS issue - slow ping interval but normal ping value

[McArthor_Lee]

i'm running ubuntu 12.04.3 x86 desktop in my corporation environment. I join the corp domain by Likewise open. But when I ping another pc, say hostname is pc-test, "ping pc-test" or "ping pc-test.domain.name" returns slow interval (about 5 seconds) but the ping value is below 1 ms. When I use "ping -n pc-test", everything works well. So I conclude this is about reverse DNS issue.

how to fix this issue? many thanks!

In my understanding, reverse DNS issue is related to DNS server or Wins server, not only an ubuntu issue, is this right?

if I wanna fix this issue as much as possible on ubuntu but not on network servers, what to do?

[SeijiSensei]

Actually it could be that your resolver is not appending the domain to "pc-test" to give a "fully-qualified domain name" like pc-test.yourdomain.name. Either this is a DHCP error, where the DNS search field is not being distributed from the network server or, less likely, an error in your local network client.

First, see if "pc-test.yourdomain.name" works without a delay while "pc-test" does not. If so, edit the file /etc/dhcp/dhclient.conf as root with sudo. You'll need to make a couple of changes to this section of the file:

#send host-name "andare.fugue.com";
send host-name = gethostname();
#send dhcp-client-identifier 1:0:a0:24:ab:fb:9c;
#send dhcp-lease-time 3600;
#supersede domain-name "fugue.com home.vix.com";
#prepend domain-name-servers 127.0.0.1;
request subnet-mask, broadcast-address, time-offset, routers,
        domain-name, domain-name-servers, domain-search, host-name,
        dhcp6.name-servers, dhcp6.domain-search,
        netbios-name-servers, netbios-scope, interface-mtu,
        rfc3442-classless-static-routes, ntp-servers,
        dhcp6.fqdn, dhcp6.sntp-servers;
#require subnet-mask, domain-name-servers;

Remove the hash mark from "supersede domain-name" and replace it with "supersede yourdomain.name". I would also remove the "domain-search" parameter from the request list. Restart the network with "sudo service networking restart".

If your machine could not resolve the name "pc-test.yourdomain.name" either, then you'll have to create static entries in /etc/hosts for machines you want to reach. Suppose that machine has address 10.10.10.10. Then you would edit /etc/hosts as root and add the line:

10.10.10.10     pc-test

Another possibility is that Likewise doesn't actually provide the Unix DNS server information to your client, just its Netbios name that Windows uses. Take a look at your /etc/network/interfaces file and see what you have for the definition of eth0. If you have a static address, you can edit that file to provide the domain-search parameter like this:

auto eth0
iface eth0 inet static
address ...
netmask ...
gateway ...
dns-search yourdomain.name

and restart networking.