The knowledge about Network Addressing is essential for a person to pass CCNA Routing and Switching 100-101 ICND1 exam as it is one of the major sections in the course outline.

What is Network Topology:

Network Topology is the way or layout in which different devices are connected to each other in a network. Network topology also defines how the information will be moved / transferred across a network.

Types of Topologies:

Following are the common types of network topologies:

  • BUS Topology
  • RING Topology
  • STAR Topology
  • MESH Topology
  • TREE Topology
  • HYBRID Topology

Here we will discuss addressing in the case of Star topology.


Server hosts the files that all other devices in the network needs. If Computer 1 needs a file form server, first of all we have to develop a mechanism through which Computer 1 can find Server in the network and for this purpose the concept of Addressing is used.

Addressing is divided into two types

  • Physical / MAC Addressing
  • Logical Addressing

There is a lot of difference between these two.  Logical is just virtual and can be changed while physical addressing is constant and can never be changed.

  1. Physical Addressing:
    The physical address is burned in the device by the manufacturer. It is a numeric value that is assigned to a particular device that is going to participate in a network that could be a router, a switch, a server, a network interface card or anything that is going to use the physical connectivity on a network to communicate. The physical address is also used to differentiate one a device manufacturer from the other.

Rules for assigning Physical address:
There are some rules for assigning a physical address. The most important is that this address is unique for each device. The reason for this is that there are a number of devices in a network and each should have different physical address so that it can be accessed easily. Suppose, if two devices have same physical address than it is impossible to distinguish between them.

Nature of Physical Address:
The physical address is hexadecimal in nature i.e it can be anything from 0 to F. The physical address is represented in three groups of values like AAAA.BBBB.CCCC. This Address is divided into two parts. The first half of the physical address represents the manufacturer of a device like Cisco or Intel and it is termed as OUI which stands for Organizational Unique Identifier, it represents 24 bits of the information. So the first 24 bits of the physical or MAC address is going to be the OUI. The second half of a physical address is going to be the serial number. It represents the device manufactured by the specific manufacturer and assigned to identify a specific device. It should be unique.

MAC Address:
MAC stands for Media Access Control. In case of wireless networking, the MAC address is used to identify a device. Suppose there are a laptop and a router in a wireless network. The router will send information to the laptop by identifying it through its unique MAC address. If we shift our laptop from one network to another, its MAC address remains the constant. We can related MAC address to the name of a person, the person’s name remain constant no matter where he goes. Same is the case with MAC address of a device.

2. Logical Addressing:
The logical addressing is categorized into two types IPV4 and IPV6. Here we’ll discuss IPV4 logical address. These are 32 bit and represented in Binary. This address is represented as 8bits.8bits.8bits.8bits. The IPV4 logical address is written in format. The IPV4 logical address ranges from 0-255 so it gives a wide range of unique logical addresses. Each device in a network has a unique logical address but it’s not constant as physical address.

Suppose is a logical address of a device in a network. 192.168.0 this part of the address represent a concerned network while .2 represent a specific device or host on that network. The logical address can be changed any time like if we move from one network to another the logical address is changed.

How it works:
The logical address works in a way that, if a device wants to communicate with another device on a network, it will send a message to the hub or switch in the network and that switch will send that message to all other devices on the network and when the message will reach to the desired device it will respond back to the sender device along with is physical address to communicate and all this is identified just because of unique logical address assigned to the receiver device.

Address Resolution Protocol:
The above discussed scenario is termed as ARP which stands for Address Resolution Protocol. ARP exists for the purpose of taking a logical address and translating it to a physical address for the purpose of sending information across a network.

Purpose of Switches:
Switches basically act as a gateway or hub between all other devices in a network. When any of the devices want to communicate with another device, the message will first sent to the switch and switch will identify that specific receiver device. Everything on the switch has that same specific network. In simple words, the switch acts as a highway that connects all of the devices on a network.

More to Learn:
Cisco CCNA 100-101 exam is based on a number of technical topics. We have also covered some other topics for the candidates. Follow the link below to get benefit from our Lesson 2 which is based on the topic of a Network

Cisco 100-101 Exam Preparation:
After getting all the technical knowledge about 100-101 exam, the candidates have to practice for better preparation of the real 100-101 exam. The practice tests are a best tool / way to prepare for the real exam as it is a simulator of a real exam.

Finding these practice exams is not an issue now as Selftest Training, a leading name in the certifications industry, provides these practice tests to ensure that the candidate should pass the 100-101 exam in first attempt.