troubleshooting of DNS
 

Hi,


I am configuring DNS for oracle rac. But when i fired command nslookup ip it display output bt when i fired nslookup hostname no respond.


root@dns1 named]# nslookup rac2.rac.com
;; connection timed out; trying next origin
;; connection timed out; no servers could be reached


Regards,
Tushar

Read the "Question Guidelines" link in my posting signature. You provide no details that would let anyone help you; version/distro of Linux, how DNS is configured further along (where does your system get ITS name information from?), etc. Also, Oracle RAC is a commercial product...since you're paying for it, have you contacted Oracle support?

nslookup is deprecated - you can use host for quick lookups or dig for more detailed information. (On Windows you still use nslookup unless you install BIND.)

You're getting a timeout which suggests that the name server you're querying isn't responding OR it isn't finding any name server to query.

What is in /etc/resolv.conf?

When I run "whois rac.com" it shows up as a Registered domain. Do you own this domain?

When I run host rac2.rac.com. it responds with:
Host rac2.rac.com not found: 3(NXDOMAIN)

When I do a "dig rac2.rac.com" it responds with:
; <<>> DiG 9.3.6-P1-RedHat-9.3.6-25.P1.el5_11.2 <<>> rac2.rac.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 17417
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;rac2.rac.com. IN A

;; AUTHORITY SECTION:
rac.com. 618 IN SOA ns1.rac.com. adam\.smith.rac.com. 1434029522 10800 3600 604800 10800

;; Query time: 3 msec
;; SERVER: 10.0.4.99#53(10.0.4.99)
;; WHEN: Wed Mar 23 15:40:24 2016
;; MSG SIZE rcvd: 81

The above shows that there is no A record for rac2 at domain rac.com.

Did you try setting up your own domain called rac.com? If you aren't the Registrant you shouldn't do that.

Also you don't have to run a name server on the same host as Oracle RAC/GRID if you already have another name server in your environment.

When we did RAC/GRID here we setup in our internal dns domain (e.g. mydomain.com) the VIP IPs and the SCAN IPs required by RAC.
e.g.
VIP of first node = racserver1 GRID VIP 10.0.70.10 racserver1-vip.mydomain.com
VIP of second node = racserver2 GRID VIP 10.0.79.11 racserver2-vip.mydomain.com
GRID Shared (SCAN) IPs racserverg-scan.mydomain.com = 10.0.70.12, 10.0.70.13 & 10.0.70.14

Hi ,


[root@dns1 data]# cat /etc/resolv.conf
# Generated by NetworkManager
search dns.com
nameserver 192.168.3.8
nameserver 172.0.0.1
options attempts: 3
options timeout: 3

Hello sir,

I am getting error in tail -100/var/log/messages

Mar 24 01:44:51 dns1 named[16121]: error (network unreachable) resolving './NS/IN': 2001:503:ba3e::2:30#53
Mar 24 01:44:51 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org/AAAA/IN': 2001:503:ba3e::2:30#53
Mar 24 01:44:54 dns1 named[16121]: error (network unreachable) resolving 'akregator.sf.net.dns.com/A/IN': 2001:7fd::1#53
Mar 24 01:44:54 dns1 named[16121]: error (network unreachable) resolving 'akregator.sf.net.dns.com/AAAA/IN': 2001:7fd::1#53
Mar 24 01:45:01 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/A/IN': 2001:7fe::53#53
Mar 24 01:45:01 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/AAAA/IN': 2001:7fe::53#53
Mar 24 01:45:04 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/A/IN': 2001:500:3::42#53
Mar 24 01:45:04 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/AAAA/IN': 2001:500:3::42#53
Mar 24 01:45:04 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/A/IN': 2001:500:2f::f#53
Mar 24 01:45:04 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/AAAA/IN': 2001:500:2f::f#53
Mar 24 01:45:04 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/A/IN': 2001:500:1::803f:235#53
Mar 24 01:45:04 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/AAAA/IN': 2001:500:1::803f:235#53
Mar 24 01:45:07 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/A/IN': 2001:dc3::35#53
Mar 24 01:45:07 dns1 named[16121]: error (network unreachable) resolving 'planetkde.org.dns.com/AAAA/IN': 2001:dc3::35#53

plz help me...........

HI,


Plz help me for this issue i am waiting for rply.

...and, less than 24 hours later...
Again, you need to read the LQ Rules and Question Guidelines. Do NOT use text speak, and don't bump your own threads. If you need 'urgent' help, then do as suggested in the very first reply, and contact Oracle...HAVE YOU??? Oracle RAC is NOT a free product, and MensaWater gave you good advice...did you look at/try/read any of it?

And again, you STILL have not told us version/distro of Linux, or any details about your environment.

The above tells it to do query against 192.168.3.8 and if that fails do it against 172.0.0.1. It also says if you don't put in a fully qualified domain name (FQDN) then append dns.com to the short name you used.
If you do "host www.google.com" or even "host google.com" it sees that as an FQDN. If you input only "host google" it sees that as a short name and would actually search for google.dns.com (which likely doesn't exist).

So now that you know what servers you're querying you have to verify they are LISTENing on port 53. You can first simply try ping on the IPs:
ping 192.168.3.8
ping 172.0.0.1
If that responds you have a path to it. If it doesn't it may be you have no path or it may be it doesn't allow ping (ICMP) traffic.

You can try doing your test directly against the IPs:
dig @192.168.3.8 rac2.rac.com
dig @172.0.0.1 rac2.rac.com

My guess is that you're not actually reaching either network on port 53 because your log tells you you're not making a network connection. Is either of these an IP on your network? Did you setup DNS on one of them?

I notice you also ignored my question as to why you're trying to use "rac.com" or whether you own that.

By the way: Did you mean to have 172.0.0.1 or is that a typo of 127.0.0.1 (localhost)? If you have configured DNS on the local server having 127.0.0.1 in the resolv.conf makes sense.