Network Basics - Part 2(continue)

Public and Private IP Address

Both of these IP addresses exist to provide unique identification to every device on the network. 

Public IP address

• Public IP address is also known as an External IP address. 
• It is provided by your Internet Service Provider (ISP) and is assigned to your home network so that your home network gets a unique identification to the outside world. Any device on the network shall be able to communicate to your home network through this IP address. 
• It is unique throughout the internet. No 2 devices on the internet have the same public IP addresses. 
• It is further of 2 types, static IP address and dynamic IP address.If your ISP issued you a static IP address, then you will enter this IP address in your router’s network settings while setting up your router and that is going to serve as a unique identification for your home network to the internet. In case of dynamic IP address, you enter DHCP (Dynamic Host Configuration Protocol) in your router’s network setting while setting up your router. DHCP tells your router to accept the IP address issued by your ISP from time to time.

Private IP address

• It provides unique identification to all the devices within your network. It is also called as an internal IP address as it is assigned to the devices within your private space(inside your network). 
• Like public IP address issued by your ISP, router issues private IP addresses to all the devices within your network so as to provide unique identification to all devices within your network.
• Private IP address enables devices within your network to communicate with one another. The network configuration settings of each device in your network is stored on DHCP, so that it can accept the IP address issued to it by the router.

Note:

As private IP address is used for unique identification of devices within your network, it is never used outside your network. Similarly, your public IP address is never used within your network. Router controls network traffic within your home network and outside of it. Router ensures that data flows to correct the places.

Public & Private IP address

In the above example of home network, we have 2 personal computers as PC1 & PC2 and 1 network printer that are connected to a switch, which in turn connected to a router. We also have a laptop which is connected to the router (wireless connectivity). All these devices - PC1, PC2, network printer, switch and laptop that are connoted to router gets a private IP address from the router via DHCP protocol, whereas router gets a public IP address issued by ISP.

Networking Basics - Part 2

Ping

Ping is a command that we can use to test connectivity to a remote site or a remote network. When connected to the internet, we access websites such as google.com, facebook.com etc. We can use the command “ping” to test connectivity to these sites. In the example below, I have used Ping command to test connectivity to www.google.co.in.

Ping command

What I have typed is www.google.co.in , but received response from 172.217.26.67 which is called an IP Address. Google.co.in is called a Domain name and it is resolved to 172.217.26.67 which is an IP Address by a Domain Name System (DNS) server. We will discuss IP Addresses, domain names, DNS in detail later. As of now, think of domain names as facebook.com, amazon.com, etc. and IP Addresses as numerical addresses such as 172.217.26.67, 54.239.17.6 etc. and Domain Name System (DNS) is a server that is telling my PC that google.co.in has this IP Address and through ping command, I am able to test my connectivity to that IP address.

Tracert

We can use this command called tracert (Trace route) on our windows PC to test the path or to find the path to site such as google.co.in as shown below.

Tracert command

This command has shown me that how many devices I have jumped across or passed through to reach to google.co.in.

Note: In Linux and Mac OS , we can use "traceroute" command for tracing the route.

IP Address (Internet Protocol Address)

• It is a numerical address assigned to every device such as a computer that connects to a computer network and uses internet protocols for communication.

• It is similar to a house address. In physical world, we have house address and street address. Similarly, in computer networking, we have an IP address.

House Address

How to know the IP Address of your computer (for Windows Operating System)

We will discuss 2 methods for finding an IP address.

1. Through control panel 
2. Through command prompt

Method 1: Through control panel

Step 1:   Open Control Panel.

Step 2:   Click on Network and Intenet à Network and Sharing Center, click on Change adapter settings.

Step 3:   Highlight and right click on Wi-Fi, go to Status àDetails. The IP address will display.

Checking IP Address via Control Panel

Note: If your computer is connected to a wired network, please click on Ethernet icon.

Method 2: Through command prompt.

Step 1:   Open Command Prompt.

Step 2:   Type “ipconfig” and press enter.

This will display your network connection information. Look for IPv4 address under Wireless adapter or Ethernet adapter (depending on if your computer is connected via Wi-Fi or Ethernet).

ipconfig command

As my computer is connected to the internet via Wi-Fi, I can see my IP Address under Wireless Adapter.

Networking Basics - Part 1

Network Interface Card (NIC)

It is a hardware component of the computer that connects our devices such as iPad, laptop etc to the network such as Internet. It is also known as Network Interface Controller, Network Adapter, LAN Adapter and Physical Network Interface.

Network Interface Card

Example:
We have a laptop connected to the network via a cable plugged into Network Interface Card and they are called as Wired Network Interface Cards. These days, we have Wireless Network Interface Cards that enable our devices to connect to the network running in the air.

Computer Network

what is a computer network? Before understanding what a computer network is, let's think about a social networking site such as Facebook.com, Twitter.com. These sites enable people to connect to each other by allowing them to communicate with one another by sharing information such as text, video, audio etc. Similarly, a Computer Network allows devices such as a laptop, computer, iPad, iPhone etc. to communicate with one another. In its simplest form, a computer network can be 2 devices such as a laptop and a computer connected to each other via a cable sharing information with each other.

Computer Network

For example, we may have a file on our computer that we want to send to another device such as a laptop. We could connect them via a cable (Ethernet cable) which is plugged into network interface card on the computer and allow them to share information with each other.

Internet

• We all use internet on daily basis, spends hours on social networking websites such Facebook.com, Twitter.com etc. 
• The Internet provides us the ability to connect to the world through these sites. Not only does it connect people through social networking sites, but it also provides us a wealth of information through websites such as Wikipedia.org, allwomenstalk.com. 
• The Internet also enables us to shop online, thereby saving us from standing in queues in a shopping mart. What actually is an "Internet"? The definition is quite simple. 
• The Internet is a "complex/massive computer network" or we can say "Network of Networks".
• It connects millions of computers together globally and forms a network in which any computer can communicate with any other computer as long as they are both connected to the internet.

Network Protocol

It is a set of rules that govern the communication between the network devices. Let's understand it in this way. Suppose there are 2 persons A and B whereas A only speaks French and B only speaks Hindi.They will not be able to communicate effectively with each other. In a similar way, a Network Protocol can be considered as a language that devices on the network use to communicate with each other.

Small Office & Home Office Network (SOHO)

SOHO is a term used to refer small office and home office environment. SOHO network is a network that supports the SOHO work environment. Unlike large businesses, small businesses do not require large networks to support themselves and their employees.They use small networks to cater to their online needs.
Below picture depicts a SOHO network.

Small Office & Home Office Network

In our home office network, we may have a router that connects the SOHO network to the public data network (internet) via a local ISP (Internet Service Provider).The router may provide wireless connectivity so that our devices such as Laptop, iPad, iPhone etc. will be connected to the network or it may provide wired connectivity so that our desktops will be connected to the network. The router may be connected to a device called Switch.

Note:
The Router receives information from 1 device and then, decides where to forward this information based on some decision criteria. Like, shall I forward this to wireless so that it can be received by the laptop or shall I forward this to the internet in case there is a request for website access such as facebook.com? The Internet is made up of thousands of routers.

The Switch is a network device that has got multiple ports (interfaces) to which multiple devices can be connected so that all devices can communicate with one another.

Let's come back to our example of a home network, we may have a router connected to a switch. The router may be providing wireless connectivity through which our devices such as a laptop, iPad etc. will be connected to the network. We may have a network printer and PC's that are physically connected to switch.

Note:
We will discuss the network devices in detail later.