Issue with vps and hostname

hello all

i did buy a vps and i did install cpanel on it

then i did register and add a record for name server

i also create a account for the domain

i can open site using

ns1.example.com its show cpanel default page
and
ns2.example.com show cpanel default page

and
the host name
ser.example.com open and show the cpanel default page

the issue that i cant open the site example.com its keep loading and never open

i try to check from proxy same issue

can any one explain why
do i need to add a record for domain example.com
and for www.example.com ?

 

i try ping normally