domain naming for exchnage server

Hello all,

I have  a newly built exchange server 2013 and DC with local domain name called grholdings.com( not broadcasting out )

but my client dns is registered as  grholdingsltd.com

Please help me, as what changes I have to make in local exchange server and DC , inorder to receive and send emails .

Note : servers will go alive next week Monday for work environment.

thank you in advance

G.Reddy

GR