Firewall in HA: how VRRP works?

[Carmelo Floridia]

Hi guru,
Assume that i have two firewalls in HA,
each firewall has 4 interface(internet,intranet, DMZ and VRRP)
In which way  can I monitor connectivity between firewall and other 3
networks?
For example, if the interface of DMZ of the master firewall goes down....or
goes down the link between master firewall and DMZ....how the backup take
the control?
best regards
Carmelo