Caching different domains?

Question

Network administration

There is domain1.zone domain2.zone
They are tied to fornex hosting to one folder, how to make it so that if a person goes to domain1 and then to domain2, then the cache on domain2 is taken from domain1

Answer 1

what is the cache in this case? cash, browser cache, memcache, session...?

Answer 2

transfer pictures to domain3.zone and upload from it for both sites. Well, or at least leave the pictures only on one site, and on the second, get from the first