How to find out my dns server addresses ?

To find your DNS server address type following command as shell prompt:

$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver xxx.xxx.xxx.xxx
nameserver xxx.xxx.xxx.xxx