A company has a main office and five branch offices located in different cities. You configure Skype for Business Enterprise Voice for the main office. You deploy a Survivable Branch Appliance (SBA) at a branch office and connect it to a public switched telephone network (PSTN) by using a T1 trunk line. You configure the SBA voice gateway to use fully qualified domain names (FQDN). You test the branch isolation by disconnecting the wide area network (WAN) form the branch office and make an outbound call. The call was successful. Next, you make an inbound call to the branch office and the call fails.
You perform the following troubleshooting steps:
✑ Trace the IncomingAndOutgoingCalls setting.
✑ Use Snooper to analyze logs.
✑ Review the syslog file form the SBA voice gateway.
You discover that messages are sent to the Skype for Business Mediation Server pool, but not received. You reconnect the WAN from the branch office and make an inbound call. The call is successful. You need to identify the configuration error that causes inbound calls to fail. What should you check?
A. the Dynamic Host Configuration Protocol (DHCP) options for the branch DHCP server
B. the route settings for the SBA voice gateway
C. the status of the DNS services for the branch office domain controller
D. the DNS settings for the SBA voice gateway