IPv4 addressing: An IPv4 address consists of four 8-bit blocks, represented in decimal or binary format. For instance, 192.168.100.1 in decimal becomes 11000000.10101000.01100100.00000001 in binary. The minimum value for a block is 0 and the maximum is 255.
192.168.100.1 = 11000000.10101000.01100100.00000001
Private networks: Special IP ranges reserved for private networks are 10.0.0.0 - 10.255.255.255, 172.16.0.0 - 172.31.255.255, and 192.168.0.0 - 192.168.255.255.
Loopback addresses: The range 127.0.0.0 - 127.255.255.255 is reserved for loopback addresses.
Subnet masks: Masks define which IP ranges belong to the same subnet. They can be written in two ways—dot-decimal notation (e.g., 255.255.255.0)
Classless Inter-Domain Routing (CIDR) notation (e.g., /24). As you increase the number of usable IP addresses within a subnet, the number of possible subnets decreases. This table helps illustrate the relationship:
| CIDR | Dot-decimal | Number of IP addresses per subnet | Usable IP addresses per subnet | Number of subnets |
|---|---|---|---|---|
| /32 | 255.255.255.255 | 1 | 0 | 256 |
| /31 | 255.255.255.254 | 2 | 0 | 128 |
| /30 | 255.255.255.252 | 4 | 2 | 64 |
| /29 | 255.255.255.248 | 8 | 6 | 32 |
| /28 | 255.255.255.240 | 16 | 14 (out of 16) | 16 |
| /27 | 255.255.255.224 | 32 | 30 | 8 |
| /26 | 255.255.255.192 | 64 | 62 | 4 |
| /25 | 255.255.255.128 | 128 | 126 | 2 |
| /24 | 255.255.255.0 | 256 | 254 | 1 |
When calculating the usable IP addresses, note that the first address is reserved as the network address and the last address is reserved as a broadcast address.
Switches: A switch allows connecting multiple devices to the same network. Its primary function is distributing packets within the network.
Routers: Routers facilitate communication between different networks. In Netpractice, routers are represented by the term "Interface." Understanding the basics of routers and switches is essential for success in this project.
Routing tables: A routing table stores various routes to networks the device is associated with. It contains two main components: the destination (represented by the network address and CIDR) and the next hop (the address of the subsequent router required for packet delivery toward the destination network).
Connecting networks: To establish connections within a network, devices must be linked, either directly or through routers shared by both networks. To determine whether two devices belong to the same network, perform a bitwise AND operation between the IP and mask of each device, then compare the results. If they match, the devices are part of the same network.