DHCP1 (New York, Scope1) and DHCP2 (Seattle, Scope2) currently serve only their own local office. To make DHCP highly available across both offices, the modern, supported approach is DHCP Failover, configured per scope (option E), which replicates lease information between DHCP1 and DHCP2 in either load-balance or hot-standby mode so that either server can service either scope ' s clients if its partner becomes unavailable. However, DHCP Failover alone only helps if a client ' s DHCP broadcast can actually reach the surviving partner server across the WAN; broadcasts do not cross routed office boundaries on their own. Configuring a DHCP relay agent on the router (or another relay-capable device) in each office (option B) forwards DHCPDISCOVER broadcasts from local clients to the remote partner server whenever the local DHCP server is down, allowing failover to actually take effect for clients in either office. The legacy split-scope technique of manually carving off a percentage of the other scope ' s addresses (options A and C) is the older, pre-failover workaround and is unnecessary once DHCP Failover is used; there is also no DHCP cluster role delivered through Windows Failover Clustering (option D), since DHCP achieves high availability through Failover mode, not a clustered role.