host command

Q. I’m not able to run nslookup or host command under Debian or Ubuntu Linux. In fact, these commands are missing from my installation. How do I install nslookup and related dns client commands?


I‘m using CentOS Linux server version 5.x/6.x+. How do I configure a system so that the DNS resolver will append search path extensions to hostnames that have dots in them? For example, my domain name is when I query for mail hostname it should append and return the IP address of hostname.