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Uniform Resource Locator - URL

A URL (Uniform Resource Locator) is a string used to uniquely identify and locate the address of a resource on the Internet or another network. A URL typically consists of several parts that specify various information about the resource:

  1. Protocol: The protocol specifies how the resource should be accessed or transferred. Common protocols include HTTP (Hypertext Transfer Protocol), HTTPS (HTTP Secure), FTP (File Transfer Protocol), and FTPS (FTP Secure).

  2. Hostname: The hostname identifies the server where the resource is hosted. This can be a domain like "example.com" or an IP address indicating the exact location of the server.

  3. Port (optional): The port is a numerical address on the server that allows access to specific services. Default ports are often used implicitly (e.g., port 80 for HTTP), but custom ports can also be specified for special services.

  4. Path: The path specifies the location of the resource on the server. It can refer to a specific directory or file.

  5. Query string (optional): The query string is used to pass additional parameters to the server that can be used to identify or customize the requested resource. The query string starts with a question mark and usually contains a series of key-value pairs separated by the ampersand (&).

Together, these parts of a URL form the complete address of a resource on the Internet or another network. URLs are used in web browsers, hyperlinks, APIs, and other internet applications to access and identify resources.

 


Slowloris Attack

A Slowloris attack is a form of a "Low-and-Slow" attack that aims to overload a web server and prevent access to it by tying up all available connections to the server. In a Slowloris attack, the attacker sends many HTTP requests to the server, but does so extremely slowly by intentionally delaying the data transfer.

Typically, the attacker opens many connections to the server and keeps them open by sending only part of the request and then leaving the connection open by sending additional parts of the request slowly or simply not sending any further data. This way, all available connections to the server are tied up, preventing legitimate users from establishing a connection since there are no free connections available.

This attack is particularly effective against web servers that do not enforce a limited number of connections per user or IP address and rely on the server's resource availability to serve requests. However, a well-configured web server can detect and mitigate such attacks.

 


Unicast

Unicast is a term in computer networking that describes the transmission of data to a single receiving address. In contrast, there's broadcast, where data is sent to all addresses in a network, or multicast, where data is sent to a specific group of addresses.

Unicast communication is typical for many Internet applications where data needs to be sent to a specific recipient, such as retrieving web pages, sending emails, or downloading files. In a unicast communication model, a sender sends data to a specific IP address, and a specific receiver responds by receiving the data and reacting to it.


Broadcast

Broadcast refers to a method of data transmission in a network where data is sent from a single source to multiple or all participants in the network. In contrast to Unicast, where data is sent from one source to a single recipient, and Multicast, where data is sent to a predefined group of recipients, in Broadcast, data is sent to all participants in the network, regardless of whether they need the data or not.

Broadcast is commonly used in networks to disseminate information that is of interest to all participants, such as ARP (Address Resolution Protocol) requests, where a device wants to identify the MAC address of another device on the network, or DHCP (Dynamic Host Configuration Protocol) requests, where devices request IP addresses from a DHCP server.

Although Broadcast provides a simple way to distribute data in the network, it can lead to network congestion, especially in larger networks, since all participants must receive the transmitted data regardless of whether it is relevant or not. For this reason, Broadcast is often used with caution in larger networks and replaced by more efficient techniques like Multicast where appropriate.

 


Multicast

Multicast is a network communication method where data is transmitted from one source to a group of recipients. Unlike Unicast, where data is sent from one source to a single recipient, Multicast enables efficient transmission of data to a pre-defined group of recipients who wish to share the data.

In Multicast, data is sent once from the source and copied by routers in the network and forwarded to all participants in the multicast group. This reduces network traffic compared to Unicast, where separate copies of the data would need to be sent to each individual recipient.

Multicast is commonly used in applications such as multimedia streaming, video or audio conferencing, distributed gaming, and software updates, where the same data needs to be sent to multiple participants simultaneously. It is an efficient mechanism for saving bandwidth and improving the scalability of network applications.

 


IP-Address

An IP address (Internet Protocol Address) is a unique numerical identifier assigned to each device connected to a computer network that uses the Internet Protocol for communication. IP addresses are used to identify devices within a network and enable them to communicate with each other.

There are two types of IP addresses: IPv4 (Internet Protocol Version 4) and IPv6 (Internet Protocol Version 6). IPv4 uses a 32-bit number, while IPv6 uses a longer 128-bit number. A typical IPv4 address looks like this: 192.168.0.1, whereas an IPv6 address is more complex, such as: 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

IP addresses are used to identify devices on the Internet and allow them to exchange data. They play a central role in routing data packets across the Internet, enabling information to be forwarded between different computers and networks.

 


Domain Name System - DNS

The Domain Name System (DNS) is a hierarchical and distributed system designed to translate human-readable domain names into machine-readable IP addresses. It facilitates communication between computers on the Internet by managing the mapping of easily memorizable domain names to the numerical IP addresses that represent the actual communication targets.

Key functions of DNS include:

  1. Name Resolution: The primary purpose of DNS is to resolve domain names to IP addresses. For example, when you access a website like "www.example.com," your computer uses DNS to find the corresponding IP address of that website.

  2. Hierarchical Structure: DNS has a hierarchical structure evident in domain names such as "example.com." The hierarchy extends from right to left, with the right side being the Top-Level Domain (TLD), like ".com" or ".org," and the left side indicating specific subdomains (e.g., "example").

  3. Distributed Database: DNS is decentralized and operates with a distributed database structure. There are multiple DNS servers distributed worldwide that collaborate to manage the mapping of domain names to IP addresses.

  4. DNS Servers: Various types of DNS servers exist, including Authoritative DNS Servers, which provide authorized information for specific domains, and Recursive DNS Servers, which handle queries from clients and, if necessary, access Authoritative DNS Servers to obtain the required information.

DNS plays a crucial role on the Internet by providing a user-friendly way to access resources without users needing to know the underlying numerical IP addresses.