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 ipconfig and specify the FlushDns parameter.

B.
Run ipconfig and specify the Renew parameter.

C.
Run dnscmd and specify the ClearCache parameter.

D.
Run Set-DnsServerResourceRecordAging.

Explanation:
We cane clear the DNS cache on the DNS server with either Dnscmd /ClearCache (from command prompt) or
Clear-DnsServerCache (from Windows PowerShell).
Technet, Dnscmd
https://technet.microsoft.com/en-us/library/cc772069.aspx