What is DNS A record?
The DNS “A” record is a fundamental component of the Domain Name System that maps a specific domain name to its corresponding IPv4 address. For example, the A record for google.com links to Google’s IP address. A records only hold IPv4 addresses; if a website has an IPv6 address, it will instead use an "AAAA" record. These records enable users to access websites using easily memorable domain names instead of numerical IP addresses. Without an A record, users would encounter errors when trying to access a URL, making it essential for web navigation. Additionally, A records can also point to subdomains, further enhancing the organization of web addresses.
See also: DNS AAAA record, domain, DNS record, IPv4
How do DNS A records work?
A records work by linking a domain name to its corresponding IPv4 address in the DNS. When a user types a URL into their browser, the DNS resolver queries the DNS server for the A record associated with that domain. The server responds with the IP address, allowing the browser to connect to the correct server and load the website. If the A record is missing, users will encounter an error instead of reaching the intended site.
Top 5 DNS A record use cases
- Looking up IP addresses: The primary use of DNS A records is to find the IP address associated with a specific domain, allowing devices to access websites without users needing to memorize IPs.
- Operating a DNSBL: Organizations often use A records to create and manage Domain Name System-based Blackhole Lists (DNSBLs), helping mail servers identify and block spam emails.
- Firewall and security appliances: A records direct traffic to firewalls and security appliances, ensuring incoming and outgoing connections are monitored and controlled.
- VPN servers: VPN providers use A records to link their domain names to the IP addresses of their servers, enabling users to connect securely to their services.
- Monitoring services: Monitoring tools rely on A records to track the availability and performance of web services by mapping domain names to IP addresses for regular checks.
