DNS Search Order

metallica1973 · 04-16-2014, 09:22 AM

I am using Ubuntu 12.04 LTS and am having trouble getting this desktop to correctly query the correct DNS servers in resolving hostnames. I disabled adding dhcp servers from the network dhcp server under /etc/dhcp/dhclient.conf

Code:

 request subnet-mask, broadcast-address, time-offset, routers,
	domain-name, host-name,
	netbios-name-servers, netbios-scope, interface-mtu,
	rfc3442-classless-static-routes, ntp-servers;

I added the correct dns servers and dns search order under /etc/resolvconf/resolv.conf.d/base && tail

base

Code:

nameserver 10.8.0.19 10.0.0.18 10.0.0.19

tail

Code:

search testdomain.local corporate.mydomain.com mydomain.local

changed the host.conf to use bind first

Code:

order bind,hosts
multi on

modified nsswitch.conf to use dns first

Code:

hosts:          files dns mdns4_minimal [NOTFOUND=return] mdns4

The domain in particular is the testdomain.local(test lab). The way I have it above, it resolves perfectly fine but there is a long delay in going to the internet. If I switch them around and make it last:

Code:

nameserver 10.0.0.18 10.0.0.19 10.8.0.19

Code:

search  corporate.mydomain.com mydomain.local testdomain.local

the internet works lightning quick but I cannot resolve anything from the testdomain.local period but everything else works fine. Help

szboardstretcher · 04-16-2014, 09:39 AM

Nice post!

Couple things:

1) Generally, we define multiple 'search domains' like this:

Code:

domain corporate.mydomain.com
search mydomain.local testdomain.local

2) There are some commands in /etc/network/interfaces involved with this setup: dns-search/dns-domain.

You can get accurate timings of the lookups with

Code:

time dig whateveryouaretesting.com

Additional thoughts... Are you using network manager? Did you disable the dnsmasq local server? Is IP6 enabled?

metallica1973 · 04-16-2014, 04:58 PM

Many thanks for the reply,

I disabled NM and dont use it(hardset everything except for ip address). I believe I disable dnsmasq local server

Code:

cupsd      650       root    9u     IPv6               9596       0t0        TCP ip6-localhost:631 (LISTEN)
cupsd      650       root   10u     IPv4               9597       0t0        TCP localhost:631 (LISTEN)
smbd       775       root   27u     IPv4               6930       0t0        TCP *:445 (LISTEN)
smbd       775       root   28u     IPv4               6932       0t0        TCP *:139 (LISTEN)
rpcbind    804       root    8u     IPv4               6940       0t0        TCP *:111 (LISTEN)
rpcbind    804       root   11u     IPv6               6943       0t0        TCP *:111 (LISTEN)
sshd       842       root    3r     IPv4               8280       0t0        TCP *:22 (LISTEN)
sshd       842       root    4u     IPv6               8285       0t0        TCP *:22 (LISTEN)
rpc.statd  845      statd    9u     IPv4               8308       0t0        TCP *:59175 (LISTEN)
rpc.statd  845      statd   11u     IPv6               8314       0t0        TCP *:57337 (LISTEN)
ypbind     964       root    5u     IPv4               8408       0t0        TCP *:717 (LISTEN)
mysqld    1089      mysql   10u     IPv4               8598       0t0        TCP localhost:3306 (LISTEN)
python    3180       root    7u     IPv4              25988       0t0        TCP *:5252 (LISTEN)
python    3189       root    7u     IPv4              25988       0t0        TCP *:5252 (LISTEN)
python    3192       root    7u     IPv4              25988       0t0        TCP *:5252 (LISTEN)
python    3192       root   12u     IPv4              26877       0t0        TCP *:4242 (LISTEN)
perl      3206      saint    7u     IPv4              25988       0t0        TCP *:5252 (LISTEN)
perl      3206      saint   13u     IPv4              26001       0t0        TCP *:1414 (LISTEN)

I didnt mess around with IPV6 settings. I will play around with what you suggested and see what I can come up with.