Multiple Banner Exchanges

[4front]

I have several Socrates sites and more every week.
They are all from a wide variety of niches. Does
the banner exchange show ads on sites by similar
content or just random across the network.

Should I put the banner exchanges on each
individual site?

[EHiatt121]

I believe it is random. There was talk while back about trying to make it relevant to the site, but I don't know that it ever did.