Operation Manual

125 NT/MPRI – Glossary
Subnet Masks (Masks)
By using subnet masks, the “host part” of an IP address class can be
changed into a subnetwork part. This part then remains unchanged by
other computers or routers. The subnet mask indicates which ranges
are to be interpreted as subnet addresses and which as computer ad-
dresses. The subnet mask is often shown in dotted-decimal notation,
but can also be expressed simply as the number of bits to be treated
as a network address. For example, a Class A address, which has a
standard subnet mask of 8 (i.e. 255.0.0.0, or eight of the 32 bits set),
can be treated as a Class B address in combination with the subnet
mask 16 (255.255.0.0) or a Class C address with the subnet mask 24
(255.255.255.0).
The following table summarizes this convention:
ntmpri-e.book Seite 125 Donnerstag, 28. Februar 2002 11:26 11