networking

When developing an IPv4 network, you need a structured design that considers several factors:
* How many subnets are required.
* How many hosts each subnet needs.
* Which devices belong to a particular subnet.
* Which parts of your network use private addresses versus public addresses.

Here's how these parts work together:
* Network Portion: Identifies the specific network the device belongs to. All devices on the same network share the same network portion.
* Host Portion: Uniquely identifies a specific device within that network.

You'll often see something called a prefix length used with an IPv4 address. This is a shorter way to identify the subnet mask, which helps define where the network portion ends and the host portion begins. For example, /24 means the first 24 bits are the network portion.

The prefix length is a simpler way to represent the subnet mask. It's written in "slash notation" (e.g., /8, /24). The prefix length tells you the number of bits set to 1 in the subnet mask. An IPv4 address is a 32-bit address. So, a /24 prefix length means the first 24 bits of the subnet mask are 1s, and the remaining 8 bits are 0s.

Here's how subnet masks and prefix lengths relate:

Here's what routers primarily do:
* Transfer packets: They move data packets from one network segment (like a LAN) to another.
* Connect LANs: A router essentially links several LANs together.
* Help form WANs: By connecting different LANs, routers are essential for creating Wide Area Networks (WANs).
* Identify the best path: Routers are smart; they figure out the most efficient route to send data packets to their final destination.
* Network segmentation: They help divide a large LAN into smaller, more manageable LANs, which is critical for network performance and security.

To figure out which bits belong to the network and which belong to the host, you use a subnet mask. A subnet mask is also a 32-bit number. Where there's a '1' in the subnet mask, the corresponding bit in the IP address is part of the network portion. Where there's a '0', it's part of the host portion.

For example, a common subnet mask is 255.255.255.0. In binary, this is 11111111.11111111.11111111.00000000.
- The '1's show that the first three octets of the IP address are the network portion.
- The '0's show that the last octet of the IP address is the host portion.