Simple Guide to Network Fundamentals - CCNA Focus

IP addresses uniquely identify devices on a network. Each device needs its own IP address to communicate.IPv4 addresses are 32-bit numbers divided into four octets, with each octet represented by a decimal number between 0 and 255.Each octet is 8 bits. For example, 192 in the first octet is represented as 11000000 in binary.IP addresses are divided into classes. The three main classes used for host addressing are A, B, and C.Class A addresses start with a number from 0 to 127 in the first octet and use a slash 8 subnet mask.Class B addresses start with 128 to 191 and use a slash 16 subnet mask.Class C addresses start with 192 to 223 and use a slash 24 subnet mask.IP addresses are also categorized as public or private. Private IP addresses are used within local networks and cannot be routed on the internet.Subnetting divides a network into smaller, manageable segments to improve performance, security, and address management.For example, a large network like 192.168.0.0/16 can be divided into smaller subnets like 192.168.1.0/24, 192.168.2.0/24, and 192.168.3.0/24.This allows data to be routed efficiently to the correct subnet.A subnet mask separates the network portion from the host portion of an IP address.For example, a subnet mask of 255.255.255.0, also written as slash 24 in CIDR notation, means the first 24 bits identify the network.With a slash 24 subnet, we can calculate important network values.The network address is 192.168.1.0, the broadcast address is 192.168.1.255, and we have 254 usable host addresses from 192.168.1.1 to 192.168.1.254.