Allow wget in iptable

Today when I was trying to do wget from my server I found it did not allow me to do it. Then I check with yum command also and found the error message "Couldn't resolve host 'some.domainname.com'". It seems the iptables rule in Server is not allowing to wget and yum.
I set new allow rule for DNS i.e port no. 53 and it works.

IPTABLE version : iptables-1.4.7-9.el6.x86_64

iptables -A OUTPUT -p udp -m udp --dport 53 -j ACCEPT