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I know.

2
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I know what you're thinking.

3
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You're really chomping at the bit to get to subnetting.

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But before we talk about it, it's better to learn the IP classes and the subnet masks first, right?

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Octets of the IP address are broken down to provide an addressing scheme that can accommodate large

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and small networks.

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So there are basically five different classes of networks, and they range from A to E.

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We're going to focus on classes A, B and C, which provide unicast addresses for networks of three

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different network sizes.

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Class D is for multicast networking and the Class C address range is reserved for future or experimental

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purposes.

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So given an IP address, its class can be determined from the three high order bits.

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And by that I mean the three leftmost bits in the first octet.

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In a class A address.

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The first octet is a network portion.

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So Class A has a major network address of 1.0.0.0 all the way through.

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127.255.255.255.

18
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The next 24 bits are for the network manager to divide into subnets and hosts as he or she sees fit.

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Class A addresses are used for networks that are more than 65,536 hosts.

20
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In a Class B address.

21
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The first two octets are the network portion.

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So class B has a major network address of 128.0.0.0 all the way through.

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191.255.255.255.

24
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Octets three and four.

25
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That means 16 bits are for local subnets and hosts.

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Class B addresses are used for networks that have between 256 and 65,534 hosts.

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And finally, in a Class C address, the first three octets are the network portion.

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Class C has a major network address of 192.0.0.0 all the way through to 23.255.255.255.

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Octet for eight bits is for local subnets and hosts.

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Perfect for networks with less than 254 hosts.