Why my Linux seems to hang at Sendmail or Httpd service screen while booting server?

It is very common that Linux server seems to hang when starting services such as Sendmail/Postfix or httpd.

The main cause for this is failure to resolve hostname i.e. Linux cannot look up the name of the machine/server via DNS lookup. Your server will boot but it will take some time and service may not work perfectly.

First, make sure the file /etc/resolv.conf has the correct values for your machine's DNS (NS1 and NS2) server ip address:

$ cat /etc/resolv.conf

Output:

nameserver 202.54.1.20
nameserver 202.54.1.22

If you are not sure about correct nameserver IP then ask your network/sys administrator for correct IPs.

Another solution is to add your hostname to /etc/hosts file, which is the static table lookup for host names.

$ cat /etc/hosts

Output:

127.0.0.1          localhost.localdomain localhost
192.168.1.21       www.cyberciti.biz portal
192.168.1.254      router.cyberciti.biz router
192.168.1.25       laptop.cyberciti.biz lappy

Above method is quite useful if you are using Linux on a network without a DNS server. If you are going to configure 192.168.1.21 as the DNS server then you need to add your hostname to /etc/hosts file.