For example, network 192.213.0.0 was once an illegal class C network. Now, the network is a legal supernet, 192.213.0.0/16. The "16" represents the number of bits in the subnet mask, when you count from the far left of the IP address. This representation is similar to 192.213.0.0255.255.0.0.
В вводных выше на самом деле сети принадлежали class C и рухтер делал предположение о размере маски по следующей логике.
Let’s use the network command without the mask to advertise these prefixes to router2. Thinking about specifying a network without a mask, we have to assume that the router is making an assumption about the network. That is, the router must be using some sort of predetermined specification to determine what network it will advertise as well as what subnet mask that prefix will have.
Class A – Has a /8 subnet mask. First octet between 1 and 126. Class B – Has a /16 subnet mask. First octet between 128 and 191. Class C – Has a /24 subnet mask. First octet between 192 and 223.
В вводных выше на самом деле сети принадлежали class C и рухтер делал предположение о размере маски по следующей логике.
Let’s use the network command without the mask to advertise these prefixes to router2. Thinking about specifying a network without a mask, we have to assume that the router is making an assumption about the network. That is, the router must be using some sort of predetermined specification to determine what network it will advertise as well as what subnet mask that prefix will have.
Class A – Has a /8 subnet mask. First octet between 1 and 126. Class B – Has a /16 subnet mask. First octet between 128 and 191. Class C – Has a /24 subnet mask. First octet between 192 and 223.