cant ping to domain name nslookup not resolve correct domain name

my domian server name is dc01801a and domain name is ad01801a. when u nslookup its resolve as below

>ad01801a

Server:dc01801a.ad01801a

Address: 10.204.56.17

Name:ad01801a.AD01801a

Adressess:10.204.56.17

But it should be as below

>ad01801a

Server:dc01801a.ad01801a

Address: 10.204.56.17

Name:ad01801a

Adressess:10.204.56.17, 10.204.56.19

If i type ad01801a. (with dot) i can get as above. How can i get it without . (dot)?

even i cant ping from outside to ad01801a. But can from local pcs in the domain.