the domain name system (dns) converts domain names to ip addresses
Domain Name System The Domain Name System (DNS) is a hierarchical decentralized naming system for computers, services, or other resources connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates more readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. By providing a worldwide, distributed directory service, the Domain Name System is an essential component of the functionality on the Internet, that has been in use since 1985.
Email Messages are exchanged between hosts using the Simple Mail Transfer Protocol with software programs called mail transfer agents (MTAs); and delivered to a mail store by programs called mail delivery agents (MDAs, also sometimes called local delivery agents, LDAs). Accepting a message obliges an MTA to deliver it,[56] and when a message cannot be delivered, that MTA must send a bounce message back to the sender, indicating the problem.
Web server Apache, IIS and Nginx are the most used web servers on the Internet.
Denial-of-service attack A wide array of programs are used to launch DoS-attacks.