Tom Reed wrote: > > > > > That's right, but then they go 0 .. 2^8 - 1. 2^8 is still 256, Tim does > > have a point there :-) > > > > For a given ipv4, if I know net addr and broadcast addr, how will I > calculate the netmask?
You can't. You can assume that the broadcast address is the last usable address in the subnet, but it's not unique. The router sets the addressable area. Without knowledge of that, you can't tell the difference between 10.3.255.243 being in a /16, a /24, a /26... In most networks, the router will tell you the information on request via DHCP. In most IPv6 networks, the router will either have DHCP or SLAAC (router solicitation/router advertisement_ available. But most is not all. -dsr-
