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
nameserver 18.104.22.168 nameserver 22.214.171.124
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
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.