best configuration for varnish and multiple IPs and vhosts?

[Chris Hecker]

I searched around for an answer to this, but wasn't able to find 
anything comprehensive, so I'll ask here.  I'm a total newbie at this 
stuff, so please let me know if I missed some obvious link.

I have a single webserver with 5 IP addresses.  Each IP has at least one 
apache-based site on it, and sometimes there are multiple on a single IP 
via NameVirtualHost.  None of the sites share any content.

What is the best varnish setup for this?  It seems there are multiple 
options:

1.  Have a single varnishd listen on all the IPs and run them all 
through a single apache port with name virtual hosts, so it's one big cache?

2.  Multiple varnish daemons, one per IP, apache listening on multiple 
ports, one per IP for the back end?

3.  Something else entirely?

I don't have a ton of memory, if that matters.  I need to use a cache 
mostly to handle spikes from being reddited and whatnot, the normal 
daily load is fine for the server.

Thanks,
Chris