Hosts with multiple IP's + scheduling standard hosts

Hi,

I've searched the archive as well as online but couldn't find a concrete answer.

How can I monitor hosts that have multiple IP Addresses?

Currently we assign a 'virtual hostname' to each IP:

IP Hostname_a IP Hostname_b IP Hostanme_c etc.

I'm sure there muct be a simpler way.

Secondly, I've seen posts that explain how to schedule checks and alerts for 'critical' hosts with "NKTIME", but is there a way to schedule check of all hosts without adding them to a 'critical' list?

We only want to check certain hosts 19:00 - 06:00 M-F for example.

Thanks, Mario