Understanding Class C Network IP Addresses

This article will finalize what I called the First Division of IPv4’s Space. Understanding Class C Network IP Addresses will show you how dividing 64 by 2 formed the last Unicast Classful C Networks. As mentioned in previous articles, there are Unicast, Multicast, and Broadcast IP Addresses. Class A, B, and C Networks’ addresses are considered Unicast, and Class D as Multicast Addresses.

Creating Class C Networks

As you probably guessed, dividing the remainder 64 by 2 will slice the what left of the Pie to more smaller Networks starting from 192.0.0.0 up to 223.255.255.0 as Classful C Networks, and of course Classful C Networks would rule 3 bytes.

64 / 2 = 32 as Remainder, and since we left of at 192, then the last number of Class C is 224, and 224 would belong to the next Class – D Networks.

This division chopped the rest of the IP space further to 2,097,152 smaller Networks.

• 128 Networks belong to Class A,
• 16,384 Networks belongs to Class B; and,
• 2,097,152 belongs to Class C.

Class C Networks will carry 2⁸ – 2 usable IP addresses per network (remember, always consider subtracting the Network Address and Broadcast Address from the total available hosts).

Presenting Class C Networks

192.0.0.0 up to 223.255.255.0 Networks can be used.

Public Range

Example of Class C Public IP Address Range

192.0.0.1 up to 192.0.0.254

Another IP Address Range from the last Class C Network

223.255.255.1 up to 223.255.255.254

Private Range

256 Networks for internal usage.

192.168.0.0 up to Network 192.168.255.0

Example of Class C Private Usable IP Address Range

192.168.0.1 up to 192.168.0.254

Up to the last Network’s IP Address Range…

192.168.255.1 up to 192.168.255.254

Note: Some people might believe that any IP Address that start with 192 is a Private IP address, that’s Not True.  192.168.x.x is the ONLY private Range in Classful C Network.

Interesting Facts

Class C represents almost 12.5% of the Original IP Space, Class B represents almost 25%, and Class A represents almost 50% of the 4 Billion IP Space. Therefore, 128 +64 + 32 = 224, 224 equal to 87.5% percent of 256. (The whole Pie)

Calculate Class C Networks

Use this formula 2²¹ = 2,097,152 Networks.

192.0.0.0 up to 192.255.255.0
193.0.0.0 up to 193.255.255.0
194.0.0.0 up to 194.255.255.0

Till you reach the last Network…

223.0.0.0 up to 223.255.255.0

Each class C range get the number of Networks since it represents 2²¹ Network places. If Class C Rules 21 places, therefore, it rules 3 bytes.

Class C Range such 193.0.0.0 will carry: first byte (2⁷) + Second byte (2⁷) + Third byte (2⁷) = 2²¹ = 2,097,152 Networks.

Usable IP addresses

Since Class C rules its network by the first, second, and third bytes, we left with One byte (00000000) for Hosts, hence, 2⁸ – 2 = 254 Usable IP addresses Per Network.

Note: 2,097,152 Networks x 254 Usable IP addresses per network = 532,676,608 (500 Hundred Million something of Usable IP addresses). 32 / 256 = .125, hence, Class C IP Addresses represent almost 12.5% of the Original IP Space.

IP Address Experiment 5 Layout

This Experiment will use192.0.0.0 as Network Address, and 192.0.0.255 as Broadcast Address.

Sam’s IP address:

IP Address:        192.0.0.1 
                   11000000.00000000.00000000.00000001
Network Address:   192.0.0.0 
                   11000000.00000000.00000000.00000000
Broadcast Address: 192.0.0.255 
                   10000000.00000000.00000000.11111111

Adam’s IP Address:

IP Address:        192.0.0.2 
                   11000000.00000000.00000000.00000010
Network Address:   192.0.0.0 
                   11000000.00000000.00000000.00000000
Broadcast Address: 128.0.0.255 
                   11000000.00000000.00000000.11111111

Sara’s IP Address:

IP Address:        192.0.0.3 
                   11000000.00000000.00000000.00000011
Network Address:   192.0.0.0 
                   11000000.00000000.00000000.00000000
Broadcast Address: 192.0.0.255
                   11000000.00000000.00000000.11111111

Up to last IP address…

John’s Main Frame IP Address:

IP Address:        192.0.0.254
                   11000000.00000000.00000000.11111110
Network Address:   192.0.0.0 
                   11000000.00000000.00000000.00000000
Broadcast Address: 192.0.0.255 
                   11000000.00000000.00000000.11111111

From the Last Network 223.255.255.0

IP Address:        223.255.255.1 
                   11100000.11111111.11111111.00000001
Network Address:   223.255.255.0 
                   11100000.11111111.11111111.00000000
Broadcast Address: 223.255.255.255
                   11100000.11111111.11111111.11111111

Up to last IP Address…

IP Address:        223.255.255.254 
                   11100000.11111111.11111111.11111110
Network Address:   223.255.255.0 
                   11100000.11111111.11111111.00000000
Broadcast Address: 223.255.255.255
                   11100000.11111111.11111111.11111111

Creating Class D Networks

Class D Networks will be used for Multicast Addresses starting from 224.0.0.0 up to 239.255.255.255 Network, since it was dedicated to Multi-casting communication, only group of devices and not like other Classes Unicast communication, Division was not set as suppose to be with previous Classes.

Multicast is a kind of Broadcast alternative, instead of sending a broadcast message that will be processed by all the devices connected at certain network, multicast message goes only to the certain group of devices because they asked for it. That’s how it works: “You ask for it and it get delivered such Imaging Server.”

The major advantage of Multicasting is saving the bandwidth, broadcasting to all devices on the network at the same time will consume all the bandwidth which might lead to “Broadcast Storm”.

As I mentioned in Course1 IP Fundamentals articles, advanced switches plays a big role in terms of Unicast, Broadcast, and Multicast which save the bandwidth. I recommend reading Ethernet LAN Standards and Ethernet MAC Addresses articles which will show you the difference between Unicast, Broadcast, and Multicast Messages.

Class E as Experimental Networks starting from 240 up to 247

• 8/2=4
• 4/2=2
• 2/2=1

Remember, Classful Networks was a very good start in the early 80’s, yet it should have been divided at the first place as Classless way instead, however, was not so late in 1993.

Otherwise, we should not have faced the depletion soon of IPv4 in 2011, although, the classless method came to save the Classful Networks, still we ran out of IPv4 in 2011. In order to shift completely or partially to IPv6, it will take us probably another 15 or maybe 20 years.

Routers and Multi-cast Networks

• 224.0.0.5 used by OSPF Routing Protocol to send Hello Messages
• 224.0.0.6 used by OSPF Routing Protocol to Address the OSPF Designated Router
• 224.0.0.9 RIP Routing Protocol
• 224.0.0.10 EIGRP Routing Protocol

Bottom line, you have to master IP Classful and IP Classless Networks and whatever goes in between, welcome to the World of IP Fundamentals – Welcome to CCNA!

What is Next?

We have seen how IPv4 Address Space got divided to smaller Networks (Slices) which called Classful Networks, however, we are not done yet. Each Network must have what is called Mask or Netmask Address to locate its hosts in the network.

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!