This is the first of a series of posts investigating the complex world of Networking.
(Thanks to Practical Networking for their informative YouTube channel, available here).
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In the context of Networking, if a device sends and receives traffic*, it is a host.
*(Amount of data moving across a computer network at any given time).
Therefore, computers, laptops, phones, printers, servers, routers and other networked devices are hosts.
Cloud servers or Internet of Things (IoT) devices are hosts too: TVs, Smart Watches, Speakers, Refrigerators… These can all be hosts.
Hosts fall into two main categories: Clients and Servers.
Clients initiate requests, Servers respond.
However, these terms are relative to a specific communication. In another communication, a Server can become the Client and vice versa.
In simpler terms, a Server is a computer with software installed which responds to requests.
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An IP address (internet protocol) represents the identity of each host. Each host must have at least one IP address to communicate over a network. Think of it as a phone number or a mail address.
This address is stamped on all communications sent by hosts.
In the message between hosts, there will be a Source address (which defines what host sent the communication, in other words the Client) and the Destination address (which defines what host should receive the communication, in other words the Server). If the Server responds back, these addresses are inverted.
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| Source |
There are two versions of IP addresses: IPv4 and IPv6.
- IPv4 addresses are 32-bit numerical labels written in the form of four sets of decimal numbers separated by periods (dots). Each decimal number is called an octet, and it represents 8 bits.
- Example IPv4 address: 192.168.0.1
- In binary, an IPv4 address is represented as 32 bits, a combination of thirty-two ones and zeros divided in four octets (e.g., 1 octet = 1000 and 1010). Every octet represents a decimal number (min 0, max 255).
- IPv6 addresses are 128 bits in length and are written as a series of hexadecimal numbers separated by colons.
- Example IPv6 address: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
- In binary, an IPv6 address is represented as 128 bits.
- IPv6 was introduced to address the limitations of IPv4, primarily the exhaustion of available IPv4 addresses due to the growth of the internet.
When assigned, IP addresses follow a hierarchy. For a set including subsets, the IP could be 10.X.X.X. A specific subset of that set might have an IP like 10.20.X.X. The subset within the subset of that particular set could potentially
possess an IP address resembling 10.20.55.X. This pattern continues
recursively.
Why is this important? Because by following the hierarchy, it is easier to pinpoint where a particular host exists. Think of a multinational enterprise with the IP 10.20.55.127: this IP might identify a host for that specific enterprise (10), which is in a specific branch office of that enterprise, such as London (20), which is assigned to a specific team, such as sales (55).
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A network is a logical grouping of hosts having similar connectivity. For example, your Wi-Fi internet is a network. All devices of your house connected to it have similar connectivity profiles grouped under one network (your Wi-Fi internet).
Network can contain other networks named subnetwork or subnets (e.g., a school having a network with a subnetwork for each class).
Networks are connected to the Internet (which actually stands for “Interconnected Networks”) to connect them to other networks.
