The DHCP_FAILOVER_RELATIONSHIP structure defines the information about a DHCPv4 server failover relationship.

 typedef struct _DHCP_FAILOVER_RELATIONSHIP {
   DHCP_IP_ADDRESS primaryServer;
   DHCP_IP_ADDRESS secondaryServer;
   DHCP_FAILOVER_MODE mode;
   DHCP_FAILOVER_SERVER serverType;
   FSM_STATE state;
   FSM_STATE prevState;
   DWORD mclt;
   DWORD safePeriod;
   LPWSTR relationshipName;
   LPWSTR primaryServerName;
   LPWSTR secondaryServerName;
   LPDHCP_IP_ARRAY pScopes;
   BYTE percentage;
   LPWSTR pSharedSecret;
 } DHCP_FAILOVER_RELATIONSHIP,
  *LPDHCP_FAILOVER_RELATIONSHIP;

primaryServer: This member is of type DHCP_IP_ADDRESS structure (section 2.2.1.2.1) and specifies the IPv4 address of the primary server in the failover relationship.

secondaryServer: This member is of type DHCP_IP_ADDRESS structure and specifies the IPv4 address of the secondary server in the failover relationship.

mode: This member is of type DHCP_FAILOVER_MODE enumeration (section 2.2.1.1.18) and specifies the mode of the failover relationship.

serverType: This member is of type DHCP_FAILOVER_SERVER enumeration (section 2.2.1.1.19) and specifies the type of failover server.

state: This member is of type FSM_STATE enumeration (section 2.2.1.1.20) and specifies the state of the failover relationship.

prevState: This member is of type FSM_STATE enumeration and specifies the previous state of the failover relationship.

mclt: This member is of type DWORD and defines the maximum client lead time (MCLT) of the failover relationship, in seconds.

safePeriod: This member is of type DWORD and specifies a safe period time in seconds, that the DHCPv4 server will wait before transitioning the server from the COMMUNICATION-INT state to PARTNER-DOWN state, as described in [IETF-DHCPFOP-12], section 10.

relationshipName: This member is a pointer of type LPWSTR that points to a null-terminated Unicode string containing the name of the failover relationship that uniquely identifies a failover relationship. There is no restriction on the length of this Unicode string.

primaryServerName: This member is a pointer of type LPWSTR that points to a null-terminated Unicode string containing the host name of the primary server in the failover relationship. There is no restriction on the length of this Unicode string.

secondaryServerName: This member is a pointer of type LPWSTR that points to a null-terminated Unicode string containing the host name of the secondary server in the failover relationship. There is no restriction on the length of this Unicode string.

pScopes: This member is a pointer of type LPDHCP_IP_ARRAY (section 2.2.1.2.46), which contains the list of IPv4 subnet addresses that are part of the failover relationship.

percentage: This member is of type BYTE and indicates the ratio of the DHCPv4 client load shared between a primary and secondary server in the failover relationship.

pSharedSecret: This member is a pointer of type LPWSTR that points to a null-terminated Unicode string containing the shared secret key associated with this failover relationship. There is no restriction on the length of this string.