You need to enable all users to log on to their computers by using the new domain name

You are the enterprise administrator for a company named Contoso, Ltd. The network consists of
one Active Directory domain named contoso.com. You have a Microsoft Exchange Server 2007
organization named Contoso. All users log on to their computers by using credentials identical to
their e-mail addresses. The company plans to change its name to A . Datum Corporation and modify
all user e-mail addresses to include a new adatum.com domain name. You need to enable all users
to log on to their computers by using the new domain name. The solution must not disrupt existing
applications on the network. What should you do first?

A.
Use the Active Directory domain Rename Tool to rename the domain to adatum.com.

B.
Use the DNS Management Console to create a new forward lookup zone named adatum.com.

C.
Create an alternative user principal name (UPN) suffix of adatum.com.

D.
Create a new accepted domain named adatum.com in the Exchange Server 2007 organization.

Explanation:
To ensure that all the network users should be able to log on to their computers by using the new
email id credentials without affecting the existing applications on the network, you need to create
an alternative user principal name (UPN) suffix of ExamKing.com. The UPN name that looks like an

email address is the deprecation of NetBIOS domain names and usernames (referred to in Active
Directory Users and Computers as “User logon name (pre-Windows 2000)”). These are (slowly) being
replaced by what ADU&C now calls “User logon name”, in the format of an email address. These
logon names are stored in Active Directory. It has a format of: username@upn-suffix. Therefore you
just create an alternative user principal name (UPN) suffix of ExamKing.com, you can achieve the
desired results.
The User Principle Name and You
http://theessentialexchange.com/blogs/michael/archive/2007/11/13/the-user-principle-name-andyou.aspx
Implementing User Principle Name Suffix
http://books.google.co.in/books?id=eo3Kj3JVql8C&pg=PA162&lpg=PA162&dq=alternative+user+pri
ncipal+name+(UPN)+suffix+&source=web&ots=AwIOUicASN&sig=RE2Wfzx9IMf0cm1TpQSor-
4NdnU&hl=en