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Computer Network 2021

The minimum number of bits that can be borrowed is 2. If you were to borrow only 1 bit,
to create a subnet, you would have only a network number (the .0 network) and a broadcast
number (the .255 network). The maximum number of bits that can be borrowed can be any
number that leaves at least 2 bits for the host number.

In Table (4-5)’s example of a Class C IP address, bits from the Host field have been
borrowed for the Subnet field.
Table 4-5 shown an example of a Subnet Address of Class C

https://www.youtube.com/watch?v=hbdT_Q9DM8w&t=28s

4.4 IP Address Assignment, Acquisition, and Hierarchy

This section discusses how network devices obtain IP addresses. For a network to keep
functioning, the IP addresses must be assigned according to a specific hierarchy. How and why
this is done are discussed in the following section.
IP addresses can be assigned either statically or dynamically. Both methods are covered
here.

4.4.1 Obtaining an Internet Address

For a host on a network to function on the Internet, it needs to obtain a globally unique
address. A host’s physical or MAC address is only locally significant. Being locally significant
means that the address can only identify the host in its own LAN. It has no meaning to any device
that is not in that LAN. IP is the most widely used global addressing scheme. It is a hierarchical
addressing scheme that allows individual addresses to be associated and treated as groups, as
shown in Figure (4-9). These groups of addresses allow efficient transfer of data across the
Internet.
There are essentially two methods for assigning IP addresses—static addressing and
dynamic addressing. The next few sections cover static and dynamic addressing. Regardless of
which addressing scheme is chosen, no two interfaces can have the same IP address. This would
cause a conflict that might cause both the hosts involved not to operate properly.

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