I did a lot of searching, but there seems to be conflicting info on what the proper netmask for an aliased IP address should be. Some of the conflicting info seems to be FreeBSD-specific. I'm looking for the "most technically proper" answer, if there is one.
I've been assigned x.x.x.168/29.
Here is eth0:
address x.x.x.170 netmask 255.255.255.248 gateway x.x.x.169
So the proper eth0:0 netmask should be
EDIT: Per the comment from Chris S, I am not using FreeBSD; I am using Debian. My understanding is that FreeBSD users should use .255 for aliases. But I could be wrong, so you should do your own research.