Calculating netmask length when combing network prefixes Say for example I combine 16 existing prefixes which have '/12' netmask length, how would I calculate the netmask length of the new address? I know how to combine 2 addresses, but not sure how to go about with this?

> I know how to combine 2 addresses...

It's the exact same "power of 2" math... 2 = 2^1, so 2 /12's equal (12-1) /11. 16 = 2^4, so 16 /12's become a (12-4) /8.

_In theory_ , in practice, the /12's may not fall on an even power of 2. See Also: [Subnet Table] x.0/12 and x.16/12 can form x.0/11, but x.16/12 and x.32/12 cannot form x.16/11 (because 16 is the middle of x.0/11)