You support a Skype for Business Server 2015 environment that has Enterprise Voice (EV). The company has opened two new

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You support a Skype for Business Server 2015 environment that has Enterprise Voice (EV).
The company has opened two new satellite branches and configured one with a Survivable Branch Appliance (SBA) and the other with a Survivable Branch
Server (SBS). Neither branch has a DNS server.
A wide area network (WAN) outage occurs and EV stopped working for the branch users.
You need to ensure that EV functionality continues in the event of WAN outages.
What are two possible ways to achieve this goal? Each correct answer presents a complete solution.

A. Enable backup Registrar discovery by configuring Dynamic Host Configuration Protocol (DHCP) option 55 on the branch site's DHCP server.
B. Enable backup Registrar discovery by configuring Dynamic Host Configuration Protocol (DHCP) option 120 on the branch site's DHCP server to point to the fully qualified domain name (FQDN) of the SBA or SBS.
C. Enable backup Registrar discovery by configuring Dynamic Host Configuration Protocol (DHCP) option 60 on the branch site's DHCP server.
D. Enable backup Registrar discovery by configuring the SBA or SBS to respond to Dynamic Host Configuration Protocol (DHCP) 120 queries.