nslookup is a part of the bind-utils package. Without bind-utils package installed, you will get the following error when you try to nslookup any domain:
[root@centos6 ~]# nslookup
-bash: nslookup: command not found
To install the nslookup in CentOS, simply run this command :
[root@centos6 ~]# yum install bind-utils
Loaded plugins: fastestmirror
Determining fastest mirrors
CentOS6.2-Repository | 1.3 kB 00:00 ...
CentOS6.2-Repository/primary | 1.2 MB 00:00 ...
CentOS6.2-Repository 3042/3042
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package bind-utils.i686 32:9.7.3-8.P3.el6 will be installed
--> Processing Dependency: bind-libs = 32:9.7.3-8.P3.el6 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: liblwres.so.60 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libisccfg.so.62 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libisccc.so.60 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libisc.so.62 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libdns.so.69 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libbind9.so.60 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Running transaction check
---> Package bind-libs.i686 32:9.7.3-8.P3.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=============================================================================================
Package Arch Version Repository Size
=============================================================================================
Installing:
bind-utils i686 32:9.7.3-8.P3.el6 CentOS6.2-Repository 177 k
Installing for dependencies:
bind-libs i686 32:9.7.3-8.P3.el6 CentOS6.2-Repository 849 k
Transaction Summary
=============================================================================================
Install 2 Package(s)
Total download size: 1.0 M
Installed size: 2.6 M
Is this ok [y/N]: n
Exiting on user Command
[root@centos6 ~]# nslookup
-bash: nslookup: command not found
[root@centos6 ~]# yum install bind-utils
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package bind-utils.i686 32:9.7.3-8.P3.el6 will be installed
--> Processing Dependency: bind-libs = 32:9.7.3-8.P3.el6 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: liblwres.so.60 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libisccfg.so.62 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libisccc.so.60 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libisc.so.62 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libdns.so.69 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Processing Dependency: libbind9.so.60 for package: 32:bind-utils-9.7.3-8.P3.el6.i686
--> Running transaction check
---> Package bind-libs.i686 32:9.7.3-8.P3.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=============================================================================================
Package Arch Version Repository Size
=============================================================================================
Installing:
bind-utils i686 32:9.7.3-8.P3.el6 CentOS6.2-Repository 177 k
Installing for dependencies:
bind-libs i686 32:9.7.3-8.P3.el6 CentOS6.2-Repository 849 k
Transaction Summary
=============================================================================================
Install 2 Package(s)
Total download size: 1.0 M
Installed size: 2.6 M
Is this ok [y/N]: y
Downloading Packages:
---------------------------------------------------------------------------------------------
Total 6.1 MB/s | 1.0 MB 00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : 32:bind-libs-9.7.3-8.P3.el6.i686 1/2
Installing : 32:bind-utils-9.7.3-8.P3.el6.i686 2/2
Installed:
bind-utils.i686 32:9.7.3-8.P3.el6
Dependency Installed:
bind-libs.i686 32:9.7.3-8.P3.el6
Complete!
Now you can start use nslookup:
[root@centos6 ~]# nslookup
> www.google.com
Server: 8.8.8.8
Address: 8.8.8.8#53
Non-authoritative answer:
www.google.com canonical name = www.l.google.com.
Name: www.l.google.com
Address: 209.85.175.105
Name: www.l.google.com
Address: 209.85.175.106
Name: www.l.google.com
Address: 209.85.175.147
Name: www.l.google.com
Address: 209.85.175.99
Name: www.l.google.com
Address: 209.85.175.103
Name: www.l.google.com
Address: 209.85.175.104
> set type=ns
> www.google.com
Server: 8.8.8.8
Address: 8.8.8.8#53
Non-authoritative answer:
www.google.com canonical name = www.l.google.com.
Authoritative answers can be found from:
l.google.com
origin = ns1.google.com
mail addr = dns-admin.google.com
serial = 1473322
refresh = 900
retry = 900
expire = 1800
minimum = 60
>