[CentOS] inconsistent DNS results - ping vs dig vs nslookup

Wed Jun 22 20:30:18 UTC 2011
Robert Henrichs <centos at henrichs.biz>

Thanks All,

   Answering multiple questions:

***
I started off with Google's DNS servers-  8.8.8.8 and 8.8.4.4 with 
the same results.  The current set were copied off other working 
wkstas on the LAN .   Same type results with "ping www.yahoo.com" and 
"ping www.yahoo.com".   Just changed it to:   (1) 8.8.4.4   (2) 
216.146.36.36   (3) 8.8.8.8

    Rebooted the box, then . . .

root at pbx:~ $ cat /etc/resolv.conf
search isp.com
   nameserver 8.8.4.4
   nameserver 216.146.36.36
   nameserver 8.8.8.8
root at pbx:~ $ ping www.henrichs.org
ping: unknown host www.henrichs.org
root at pbx:~ $ ping www.yahoo.com
ping: unknown host www.yahoo.com
root at pbx:~ $ ping yahoo.com
ping: unknown host yahoo.com
root at pbx:~ $ ping microsoft.com
ping: unknown host microsoft.com
root at pbx:~ $ ping lilug.org
ping: unknown host lilug.org
root at pbx:~ $ ping centos.org
ping: unknown host centos.org
root at pbx:~ $

   what's a good link to read about how the resolv.conf file is 
constructed?  esp. the "search" entry?

***
This was part of the wget response:
www.henrichs.org        canonical name = ehost-services119.com.
Name:   ehost-services119.com
Address: 69.64.155.165

Doesn't the "address: Address: 69.64.155.165" indicate a correct result?

***
My nsswitch.conf file does contain:
  hosts:      files dns
(this is an interesting file I'll have to revisit...thanks).

***

It was suggested off-list that I show "the contents of 
/etc/resolv.conf and a little history on your ifcfg-ethx files in
/etc/sysconfig/network-scripts/"

     Here is /etc/resolv.conf:
root at pbx:/etc/sysconfig/network-scripts $ cat /etc/resolv.conf
search isp.com
   nameserver 216.146.35.35
   nameserver 216.146.36.36
   nameserver 8.8.8.8
root at pbx:/etc/sysconfig/network-scripts $

     Here are the files in my /etc/sysconfig/network-scripts directory:
root at pbx:/etc/sysconfig/network-scripts $ ls
ifcfg-eth0   ifdown-ippp   ifdown-ppp     ifup          ifup-ib 
ifup-isdn   ifup-routes    init.ipv6-global
ifcfg-lo     ifdown-ipsec  ifdown-routes  ifup-aliases  ifup-ippp 
ifup-plip   ifup-sit       net.hotplug
ifdown       ifdown-ipv6   ifdown-sit     ifup-bnep     ifup-ipsec 
ifup-plusb  ifup-sl        network-functions
ifdown-bnep  ifdown-isdn   ifdown-sl      ifup-eth      ifup-ipv6 
ifup-post   ifup-tunnel    network-functions-ipv6
ifdown-eth   ifdown-post   ifdown-tunnel  ifup-hdlc     ifup-ipx 
ifup-ppp    ifup-wireless
root at pbx:/etc/sysconfig/network-scripts $

    Here is the contents of the ifcfg-eth0 file:
root at pbx:/etc/sysconfig/network-scripts $ cat ifcfg-eth0
# Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+
DEVICE=eth0
TYPE=ethernet
BOOTPROTO=none
BROADCAST=192.168.70.255
IPADDR=192.168.70.40
NETMASK=255.255.255.0
GATEWAY=192.168.70.2
HWADDR=00:1D:7D:26:31:D0
ONBOOT=yes
DHCP_HOSTNAME=pbx.local
root at pbx:/etc/sysconfig/network-scripts $



Robert Henrichs.






At 12:42 PM 6/22/2011, you wrote:
>robert henrichs wrote:
> > I am getting what I believe to be inconsistent replies/results from
> > my CentOs machine, trying to ping URLs.  Pinging by URL fails the DNS
> > lookup, while pinging the IP address (that should have been returned)
> > works.  The DNS lookup also fails NSLOOKUP, but interestingly, dig
> > and wget return A records with the correct IP.
> >
> > Robert Henrichs.
> >
>wget has *not* returned correct IP! Only nslookup and dig.
>
>First try to use only google DNS servers: 8.8.8.8 and 8.8.4.4, and if
>that does not help, and your only problem is with only that domain, you
>will have to contact support where domain is parked, and see is that helps.
>
>Only relevant info is in resolve.conf, there is no need to look at
>network configuration if you can ping IP's.
>
>Ljubomir
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