You work as the network administrator at Domain.com. The Domain.com network consists of a single Active Directory forest containing a single domain named Domain.com. Domain.com has
its headquarters located in London and branch office located in Paris. All servers on the Domain.com network run Windows Server 2008 and all client computers run Windows Vista.
Domain.com currently makes use of a computer named CERTKILLER-SR01 which has the DNS server role installed. During the course of the day whilst performing routine maintenance you discovered a few stale resource records in the Domain.com zone. You later decided to enable scavenging on CERTKILLER-SR01 to get rid of the stale records. A month later you during your security maintenance you discover that the same stale records still exist. Domain.com wants you to ensure that the stale records are removed from the Domain.com zone.
What should you do?

A.
You should consider having the dnscmd CERTKILLER-SR01 /AgeAllRecords command run at the command prompt.

B.
You should consider having the DNS service on CERTKILLER-SR01 stopped and restarted.

C.
You should consider having the dnscmd CERTKILLER-SR01 /StartScavenging command run at the command prompt.

D.
You should consider having scavenging enabled on the Domain.com zone.

Explanation:
You again noticed the same stale resource records still lay Domain.com even after enabled DNS scavenging on CERTKILLER-SR01 because the CERTKILLER-SR01 may not have Domain.com zone integrated with ADDS and loaded at the server.
To ensure that the stale resource records are removed from na.Domain.com, you need to enable DNS scavenging on the Domain.com zone. The aging and scavenging can be configured for specified zones on the DNS server to make sure that the stale records are removed from the specified zone.
Reference : Enable Aging and Scavenging for DNS
http://technet2.microsoft.com/windowsserver2008/en/library/7972082c-22a1-44fc-8e39- 841f7327b6051033.mspx?mfr=true