Internet and computer basics

DNS (Domain Name System)

The system that looks up the number of the computer you want to reach (its IP address) from a domain name, like finding a phone number by name in a phone book. Every time you open a site or send an email, your computer or phone asks a DNS server and then connects to the number in the answer. The answers come from each domain name's DNS records. Almost everything on the internet relies on DNS: if it stops, sites and email stop working too. An attacker who takes over the account that manages a domain name can change its DNS records, so that even the correct URL leads to a fake site (DNS hijacking). DNSSEC adds a mark that only the domain name's managers can make (a digital signature) to the answers, so that a forged answer swapped in along the way can be detected.