Additional interface IP MASK config

Question

Hi 
 OK I'm setting up virtual webservers to rev proxy some internal sites to external users and I have a question about the MASK config for the additional IP. 
 I've seen additional address IPs added with /24 but I would have thought that they should be added with /32 because this is an additional IP and not a group of IPs? 
 To give more details, our UTM is in a backend firewall config (e.g. isn't an edge firewall) and I'm adding an additional IP to my DMZ interface to use for an edge firewall IP to IP NAT rule so that I can rev proxy website on an internal webserver. 
 thanks 
 Mark

BAlfson · Accepted Answer

Mark, since WebAdmin does it's own magic, you don't need anything other that a /32. In fact, unlike other brands of routers, you can even use /32 in a WAN interface definition. The config daemon will make the rules necessary for the UTM to be able to reach its default gateway. 
 Sometimes, you can cause difficult-to-solve routing problems by choosing anything larger than /32. 
 Cheers - Bob