You need to ensure that your DNS servers can resolve partners.adatum.com to the correct IP address immediately

Your network contains an Active Directory forest named contoso.com.
Users frequently access the website of an external partner company. The URL of the website is
http://partners.adatum.com.
The partner company informs you that it will perform maintenance on its Web server and that the IP
addresses of the Web server will change.
After the change is complete, the users on your internal network report that they fail to access the
website. However, some users who work from home report that they can access the website.
You need to ensure that your DNS servers can resolve partners.adatum.com to the correct IP
address immediately.
What should you do?

A.
Run dnscmd and specify the CacheLockingPercent parameter.

B.
Run Set-DnsServerGlobalQueryBlockList.

C.
Run ipconfig and specify the Renew parameter.

D.
Run Set-DnsServerCache.

Explanation:
The Set-DnsServerCache cmdlet modifies cache settings for a Domain Name System (DNS) server.
Run Set-DnsServerCache with the -LockingPercent switch.
/ -LockingPercent<UInt32>
Specifies a percentage of the original Time to Live (TTL) value that caching can consume.
Cache locking is configured as a percent value. For example, if the cache locking value is set to 50,
the DNS server does not overwrite a cached entry for half of the duration of the TTL. By default, the
cache locking percent value is 100. This value means that the DNS server will not overwrite cached
entries for the entire duration of the TTL.
Note. A better way would be clear the DNS cache on the DNS server with either Dnscmd /ClearCache
(from command prompt), or Clear-DnsServerCache (from Windows PowerShell).

Set-DnsServerCache
http://technet.microsoft.com/en-us/library/jj649852.aspx
Incorrect:
Not A. You need to use the /config parameter as well:
You can change this value if you like by using the dnscmd command:

dnscmd /Config /CacheLockingPercent<percent>