It isn't written very well. The MX's use VRRP, which in essence is a virtual IP. The IP address is always serviced by the primary MX. The spare takes over the VRRP IP address if the primary fails.
It isn't written very well. The MX's use VRRP, which in essence is a virtual IP. The IP address is always serviced by the primary MX. The spare takes over the VRRP IP address if the primary fails.
The WAN interfaces each need their own IP address, and if there is a common subnet, you can also enable a Virtual IP. Using a virtual IP on the WAN interfaces is an optional configuration.