Your network contains two Active Directory forests named contoso.com and adatum.com.
Both forests contain multiple domains. All domain controllers run Windows Server 2012 R2.
Contoso.com has a one-way forest trust to adatum.com. A domain named paris.eu.contoso.com
hosts several legacy applications that use NTLM authentication. Users in a domain named
london.europe.adatum.com report that it takes a long time to be authenticated when they attempt
to access the legacy applications hosted in paris.eu.contoso.com.
You need to reduce how long it takes for the london.europe.adatum.com users to be
authenticated in paris.eu.contoso.com. What should you do?

A.
Create a shortcut trust.

B.
Create an external trust between the forest root domains.

C.
Disable SID filtering on the existing trust.

D.
Create an external trust.

Explanation:
A)
Shortcut trusts are one-way or two-way, transitive trusts that can be used when administrators
need to optimize the authentication process. Authentication requests must first travel a trust path
between domain trees, and in a complex forest this can take time, which can be reduced with
shortcut trusts.
B)
Use external trusts to provide access to resources located on a Windows NT 4.0 domain or a
domain located in a separate forest that is not joined by a forest trust.
C)
Filters users or SIDs from one domain
D)
Use external trusts to provide access to resources located on a Windows NT 4.0 domain or a
domain located in a separate forest that is not joined by a forest trust
http://technet.microsoft.com/en-us/library/cc737939(v=ws.10).aspx
http://technet.microsoft.com/en-us/library/cc775736(v=ws.10).aspx
http://technet.microsoft.com/en-us/library/cc772633(v=ws.10).aspx