Looking at the below - (This could be any addressing and assume all ACLs are in place etc.. for the traffic flow)
interface Gi0/1
nameif WAN
security-level 100
ip address 10.99.0.1 255.255.255.0
interface Gi0/1
nameif DMZ
security-level 50
ip address 192.168.66.1 255.255.255.0
object network OBJ_VENDOR
subnet 192.168.66.0 255.255.255.0
object network OBJ_HIDE
host 10.44.0.1
nat (dmz,wan) source static OBJ_VENDOR OBJ_HIDE no-proxy-arp
If I have the above NAT, when matching traffic leaves this Firewall, does it leave with a source address of the OBJ_HIDE (10.44.0.1) or does it leave the Firewall with the address of the WAN Interface IP (10.99.0.1) ?