# Webservers

Source: https://wisconsin.twango.dev/sp25-cs400/topics/webservers

# Webservers

## IP Addresses

An IP address is a unique identifier for a device on a network.

There are specific ranges of IP addresses that are reserved for private networks. These addresses are not routable on the public internet and are used for internal communication within a local network.

| Address Block                 | CIDR Notation | Default Subnet Mask | Notes                                    |
|-------------------------------|---------------|---------------------|------------------------------------------|
| 10.0.0.0 – 10.255.255.255     | `/8`          | 255.0.0.0           | Class A private network (≈16 M hosts)    |
| 172.16.0.0 – 172.31.255.255   | `/12`         | 255.240.0.0         | Class B private network (about 1 M addresses)   |
| 192.168.0.0 – 192.168.255.255 | `/16`         | 255.255.0.0         | Class C private network (about 65 K addresses) |


### Loopback Address

The loopback address is a special IP address that is used to test network applications on the local machine. It is typically represented as `127.0.0.1`, and is also known as `localhost`. When a program sends data to this address, it is sent back to the same machine, allowing developers to test network applications without needing a physical network connection.

## Ports

A port is a logical connection point for network communication. It is used to identify a specific process or service on a device. Ports are represented as 16-bit unsigned integers, ranging from 0 to 65535.

## HTTP (Hypertext Transfer Protocol)

HTTP is the protocol used for transferring data over the web. It is a request-response protocol, where a client (usually a web browser) sends a request to a server, and the server responds with the requested data.

By default, HTTP uses port `80` for communication. However, HTTPS (HTTP Secure) uses port `443`, which adds a layer of security by encrypting the data being transferred.

## Connections

- [[sp25-cs400/topics/index|Topic index]]

Obvious technical and formatting errors repaired.