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IP Addressing and Subnetting 235
IP Addressing and Subnetting
Probably no one reading this would be shocked to hear that IP addressing is one of the most
important topics on the CCNA exam. A comfortable, confident understanding of IP addressing
and subnetting is required for success on any Cisco certification. For CCNA, questions directly
ask for your interpretation of an address, its network number, its subnet number, the other IP
addresses in the same subnet, the broadcast address, and the other subnets that could be used if
the same mask were in use. In other words, you had better know subnetting!
This section of the book provides two key functions. First, you will find an extensive review of
IP addressing and subnetting. Second, this section takes a structured look at how to answer
CCNA IP addressing questions. No other topic will be covered as extensively as IP addressing
and subnetting on the exam. This section helps you prepare for answering those questions
confidently and quickly.
IP Addressing Review
To pass the CCNA exam, you must have complete familiarity with the terminology used with
IP addressing. This terminology can sometimes get in the way of a good understanding of IP
addressing. Table 5-8 lists the IP terms used in the upcoming sections.
Table 5-8
IP Addressing Terminology
Term
Definition
IP address
32-bit number, usually written in dotted decimal form, that uniquely
identifies an interface of some computer.
Host address
Another term for IP address.
Network
The concept of a group of hosts.
Network number
A 32-bit number, usually written in dotted decimal form, that represents
a network. This number cannot be assigned as an IP address to an
interface of some computer. The host portion of the network number has
a value of all binary 0s.
Network address
Another name for network number.
Broadcast address
A 32-bit number, usually written in dotted decimal form, that is used to
address all hosts in the network. The host portion of the broadcast
address has a value of all binary 1s. Broadcast addresses cannot be
assigned as an IP address.
Subnet
The concept of a group of hosts, which is a subdivision of a network.
Subnet number
A 32-bit number, usually written in dotted decimal form, that represents
all hosts in a subnet. This number cannot be used as an IP address for
some computer's interface.
Subnet address
Another term for subnet number.
continues
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