IP Addressing

IP Addressing , ?

Common Networking problems and solutions: Understanding Networking

  1. Do not confuse 0 with o on your keyboard, the address 192.168.o.1 is not valid in networking.

Confusing 0 with o on your keyboard, the address 192.168.o.1 will not work in networking but will work if the right addressing scheme is used. Note that this address is the router address and is not usable on your computer. Only enter this address in the gateway sections of your TCP/IP configurations.

 Other typo errors that will not work in networking

Always confirm that you do not add an extra digit to the group of 8 octets. i.e. use format for all IPv4 addressing.

  1. Conflicting IP addresses – Always remember that Ip addresses should not be shared

If similar Ip addresses are used for devices in the same network. A conflict message will be obtained.

  • Invalid IP Addresses

Note that IP addresses that start with 0, 1 and 255 cannot be used as they are reserved for network, gateway and broadcast respectively. The first part of an IP addresses in a network must match in all devices. I.e. for network 0, the network address 192.168.0 must match in all devices using IP addresses in the network

  1. Fault network card

To check if your network card is fault. Click start, Open run, type cmd in the run box and press enter. When the black screen appears, type ping in the black screen.  If you get replies, this means that your network card is Ok and the problem somewhere else.

You can also use this method to check if you can connect to the internet. To check this, type ping google.com in the same black screen. If you get replies, this means your computer is connected to the internet.

  1. Resolving simple network problems

Right click on the wireless network icon on the menu bar, click select open network and sharing center, select change adapter settings and then right click on the network icon and select disable. Re-enabling the network will solve your network problem.

Default Gateway IP Addresses

The gateway is the destination for internet traffic that comes from your computer going to the internet and then back with a reply of the page you wanted. The gateway is used due to unavailability of enough IPv4 addresses. Each organization or home has only one public IP address allocated by the internet service provider (ISP) that can communicate to the external network or internet. All addresses that start with 192.168 are converted to the public IP addresses in a process known as Network address translation (NAT) that takes place in the router provided by the ISP.

Samples of gateway IP addresses

If Network is 0   the gateways is
If Network is 1 the gateways is
If Network is 2 the gateways is
If Network is 3 the gateways is

and so on and so on

What or means.

To understand how a network works and why an IP address like or is needed in a network. It is important to understand how network devices are identified in a network. Network devices are identified in a network using two addressing schemes. The Mac Addressing scheme and the IP addressing scheme.

What is IP addressing and why is its important in a network.

An IP address is allocated to a network device either manually or automatically. The DHCP server is a program/service installed in managed routers to allocate IP addresses automatically to all devices in the same network that are enabled for DHCP. These devices can either be routers, switches, computers, IP phones, printers, scanners among other devices in the network.

What or mean

You probably have heard about migration from IPv4 to IPv6. The above addresses are categorized as IPv4. Ipv4 is classified further into Class A, Class B, Class C , Class D and Class E network address ranges.  The following are the ranges for various classes of IPv4 ip address.

Class 1st Octet Decimal Range 1st Octet High Order Bits Network/Host ID (N=Network, H=Host) Default Subnet Mask Number of Networks Hosts per Network (Usable Addresses)
A 1 – 126* 0 N.H.H.H 126 (27 – 2) 16,777,214 (224 – 2)
B 128 – 191 10 N.N.H.H 16,382 (214 – 2) 65,534 (216 – 2)
C 192 – 223 110 N.N.N.H 2,097,150 (221 – 2) 254 (28 – 2)
D 224 – 239 1110 Reserved for Multi-casting
E 240 – 254 1111 Experimental; used for research


Based on the table above, Ip addresses that start with 192 fall in the category of Class C network addresses which is the commonly used class of IP addresses because it accommodates only 252 addresses (i.e. 255 Less gateway and Broadcast addresses). Using a class with 255 IP addresses ensures that and organization can have many networks of 252 hosts per network.This is common in many organizations today.

What does through addressing scheme mean?

The addressing scheme of through IP addresses means that the first address in the network is and the last usable IP address when class C networking scheme is used is first address is and is reserved for network identification, the address is also reserved for the  router interface that serves as a gateway  for the network.

A gateway is a destination for all packets that are not meant for the local network. The gateway makes decisions of which interface to forward packets to based on the ip address embedded in each packet it receives.

What is the difference between and  and and

In addition to the fact that these are different IP addresses, there is another major networking difference. In networking, if different computers are given the IP addresses shown above, they will not be able to communicate unless there is a router well configured to help them communicate.

Note that all the above addresses are gateway addresses since they end with one. We need to get Ip addresses with the last digits between 2 to 253 although even after that no communication will take place.

Lets say we make all of the above IP addresses to end with .2. They become , and and In this case, the only thing that makes these IP addresses unusable is because these  are in different networks. I.e. Network 0 , 1, 2 and 10 .

To identify the network segment of any IP address, look for the first six digit of the IP address given. For instance, the IP address  is in the network . All computers in that network must start with 192.168.1.xx . The xx is a number between 2 – 253. The xx number cannot be used by two devices in the same network at the same time and all devices in this example network must have IP addresses that start with 192.168.1 .

If we were to use 192.168.2 in an IP address, this becomes another network and a router is needed for communication  to take place. Note that computers can interchange their IP addresses just like the way students can change sitting positions in a class. The only static network addressing scheme is the Mac-Addressing.

What is a Mac-Addresses

First of all, all  devices in any given network are identified by their Mac-addresses. A Mac address is a permanent hexa-decimal number allocated to a device by the manufacturer for easier identification and to differentiate devices in network and internet. In real life scenario, a mac address  is like the serial number of your birth certificate. To check the mac address of your windows computer, go to start, select run then type cmd and press enter. A black screen should appear, type ipconfig /all on the black screen and then press enter to get your network settings. Scroll the black screen until you find the physical address of the computer. This physical address is the Mac-address of your computer and is unique to it.

A Mac address is of local importance and is used to identify the source of any data frame originating from a network to ensure that replies are sent to the right devices.