Understanding Class B Network IP Addresses

Continue dividing, Understanding Class B Network IP Addresses will go through dividing the 128 remainder further to smaller Networks, which will lead to Classful B Networks, however, there will be another remainder as well to create Class C Networks. So, If you haven’t followed the process from the beginning, I recommend you read Understanding IP Addressing System Article first to link all dots together.

Creating Class B Networks

Dividing the remainder 128 by 2 will slice the rest of the Pie to even smaller Networks staring from 128.0.0.0 up to 191.255.0.0 Class B Networks, keep in mind that Class B Networks rules 2 bytes.

128 / 2 = 64 as Remainder, and since we left of at 128, then the last number of Class B is 191, and 192 would belong to the next Class – C Networks.

Adding 128 to 64 = 192, therefore, 192 from the computer perspective would belong to the next Class – C Networks. Now we have 128 Networks belong to Class A and 16,384 Networks belongs to Class B. Each Class B Network will carry 2¹⁶ – 2 usable IP addresses (Hosts).

Presenting Class B Networks

128.0.0.0 up to 191.255.0.0 Networks can be used as Class B Networks.

Public Range

Example of Class B Public IP Address Range

128.0.0.1 up to 128.0.255.254

Another IP Address Range from the last Class B Network

191.255.0.1 up to 191.255.255.254

Private Range

16 Networks dedicated for internal usage.

172.16.0.0 with Broadcast 172.16.255.255

Up to last network…

172.31.0.0 with Broadcast 172.31.255.255

Example of Class B Private Usable IP Address Range

172.16.0.1 up to 172.16.255.254

Up to the last Network’s IP Address range…

172.31.0.1 up to 172.31.255.254

Note: Some people might believe that any IP Address that start with 172 is a Private IP address, that’s Not True. The 172.16.x.x up to 172.31.x.x are ONLY the private Range in Classful B Network.

Calculate Class B Networks

To calculate the Class B Networks: use this formula 2¹⁴ =16,384 Networks.

128.0.0.0 up to 128.255.0.0
129.0.0.0 up to 129.255.0.0

Next…

130.0.0.0 up to 130.255.0.0

Till you reach the last Network…

191.0.0.0 up to 191.255.0.0

Each Class B range gets so such number of Networks since it represents 2¹⁴ Network places. If Class B Rules 14 places, meaning: it rules 2 bytes.

So a Class B Range such 128.0.0.0 would carry: first byte (2⁷) + Second byte (2⁷) = 2¹⁴ = 16,384 Networks.

Usable IP addresses

Since Class B rules first and second bytes, we left with the third and fourth bytes for Hosts (00000000.00000000), 2¹⁶ = 65,536 – 2= 65,534 Usable IP address Per Network.

Note: 16,384 Networks x 65,534 Usable IP addresses per network = 1,073,709,056 (1 Billion something of Usable IP addresses). 64 / 256 = .25, hence, Class B IP addresses represent almost 25% of the Original IP Space.

IP Address Experiment 4 Layout

This Experiment will use 128.0.0.0 as Network Address, and 128.0.255.255 as Broadcast Address.

Sam’s IP address:

IP Address:        128.0.0.1 
                   10000000.00000000.00000000.00000001
Network Address:   128.0.0.0 
                   10000000.00000000.00000000.00000000
Broadcast Address: 128.0.255.255 
                   10000000.00000000.11111111.11111111

Adam’s IP Address:

IP Address:        128.0.0.2
                   10000000.00000000.00000000.00000010
Network Address:   128.0.0.0
                   10000000.00000000.00000000.00000000
Broadcast Address: 128.0.255.255
                   10000000.00000000.11111111.11111111

Sara’s IP Address:

IP Address:        128.0.0.3
                   10000000.00000000.00000000.00000011
Network Address:   128.0.0.0
                   10000000.00000000.00000000.00000000
Broadcast Address: 128.0.255.255
                   10000000.00000000.11111111.11111111

Up to last IP address of Network 128.0

John’s IP Address:

IP Address:        128.0.255.254
                   10000000.00000000.11111111.11111110
Network Address:   128.0.0.0
                   10000000.00000000.00000000.00000000
Broadcast Address: 128.0.255.255
                   10000000.00000000.11111111.11111111

IP Addresses from Network 191.255.0.0

IP Address:        191.255.0.1
                   10111111.11111111.00000000.00000001
Network Address:   191.255.0.0
                   10111111.11111111.00000000.00000000
Broadcast Address: 191.255.255.255 
                   10111111.11111111.11111111.11111111

Up to last IP Address of network 191.255

IP Address:        191.255.255.254
                   10111111.11111111.11111111.11111110
Network Address:   191.255.0.0
                   10111111.11111111.00000000.00000000
Broadcast Address: 191.255.255.255
                   10111111.11111111.11111111.11111111

Note: Network Address a.k.a Netmask Address or Subnet Mask

Next, let’s look at how Class C Networks created from the 64 remainder.

Subject Related

By Wikipedia Classful Networks | Router Ally IPv4 | HighTech IPv4 Addressing | The TCP IP Guide | Cisco CCNA Simplified | Cisco CCNA in 60 Days | CCNA R&S Certification Kit | Subnetting Made Easy | Who is Running the Internet | IP Addressing and Subnetting | The Only IP Book You Will Ever Need!

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