Your company has a main office and two branch offices. Domain controllers in the main  office host an Active Directory-Integrated zone. The DNS servers in the branch offices host a secondary zone for the domain and use the main office DNS servers as the DNS Master servers for the zone. Each branch office has an application server. Users access the application server by using its fully qualified domain name. You need to ensure that users in the branch offices can access their local application server even if the WAN links are down for three days. What should you do？（）

• A、 Increase the Expires After setting to 4 days on the Start of Authority （SOA） record for the zone.
• B、 Increase the refresh interval setting o 4 days on the Start of Authority （SOA） record for the zone.
• C、 Configure the Zone Aging / Scavenging Properties dialog box to enable Scavenge State resource records， and set the refresh setting to 4 days.
• D、 Configure the Zone Aging / Scavenging Properties dialog b ox to enable Scavenge Stale resource records， and set the No-refresh interval setting to 4 days.