characteristics of interface type dummy

I've configured an interface 'nonlocal' with type dummy ip link add nonlocal type dummy on that interface are some IPv6 addresses configured. Now an apache can start with some ip based vhosts on above-said ipv6 addresses. The "real" addresses get configured on the phyiscal interface if a second machine crashes (failover). Everything works a expected. But I would like to know the exact characteristics of such a dummy interface (on RHEL6 & 7). Is there a homepage or something similar which explains that type?