Technical Tip: Setting up FortiGuard DDNS Redundancy for Same Domain Name

[adimailig]

Description	This article describes that it is possible to configure FortiGate to monitor more than one interface for the same Fortiguard DDNS domain. It acts as a redundancy in case the first monitored interface went down or a connection issue happens.
Scope	FortiGate, FortiGuard DDNS.
Solution	Configure DDNS to monitor more than one port. With this configuration, the FortiGuard DDNS connection will only failover to the second interface when the first interface went down. config system ddns     edit 1         set ddns-server FortiGuardDDNS         set ddns-domain "sampledomain.fortiddns.com"         set monitor-interface <interface-name1>, <interface-name2>, ...        next end Sample Configuration: config system ddns     edit 1         set ddns-server FortiGuardDDNS         set ddns-domain "adimailig1.fortiddns.com"         set monitor-interface "port1" "port2"     next end IP=10.47.3.242->10.47.3.242/255.255.240.0 index=3 devname=port1 IP=10.47.19.242->10.47.19.242/255.255.240.0 index=4 devname=port2 Port1 is UP:  > adimailig1.fortiddns.com Server: dns.google Address: 8.8.8.8 Non-authoritative answer: Name: adimailig1.fortiddns.com Address: 10.47.3.242 Port1 goes DOWN: > adimailig1.fortiddns.com Server: dns.google Address: 8.8.8.8 Non-authoritative answer: Name: adimailig1.fortiddns.com Address: 10.47.19.242 Port1 went back: > adimailig1.fortiddns.com Server: dns.google Address: 8.8.8.8 Non-authoritative answer: Name: adimailig1.fortiddns.com Address: 10.47.3.242 It is also possible to use the public IP address of the WAN instead. More details of this can be found at:Technical Tip: DDNS update with public IP on internal firewalls Note: For logically detecting Internet links up or down and failover accordingly, configurethe  link-monitor feature as outlined in this KB article: Technical Tip: Link-Monitor Explained - Fortinet Community