What is an A-Record
An A-Record (Address Record) is a type of DNS (Domain Name System) resource record that is used to translate a domain name into an IPv4 address. It is one of the most basic and most commonly used types of DNS records.
Here are some important points about the A-Record:
Resolution of domain names: The main purpose of an A-record is to create a link between a domain name (such as www.beispiel.com) and an IP address (such as 192.0.2.1). When someone enters a URL in their browser, the DNS system uses A records to find the corresponding IP address so that the browser knows where to send the request.
Syntax: An A-record consists of several fields, including:
- Name: The domain name to be resolved.
- TTL (Time to Live): The amount of time the record should remain in the cache.
- Class: Normally this is "IN" for Internet.
- Type: In this case "A" for Address Record.
- Address: The IPv4 address to which the domain is assigned.
Example of an A-record:
example.com. 3600 IN A 192.0.2.1
In this example, "example.com." specifies the domain name, "3600" is the TTL in seconds (here 1 hour), "IN" stands for the Internet class, "A" specifies the type of record, and "192.0.2.1" is the assigned IPv4 address.
function in the DNS system: When a user calls up a domain such as "example.com", their computer sends a request to a DNS resolver. This resolver then queries various DNS servers one after the other until it finds an A record that resolves "example.com" into an IP address. This IP address is then sent back to the browser, which establishes the connection to the web server.
A-Records are essential for the functionality of the Internetas they form the basis for navigation via domain names, which are easier for people to remember than numerical IP addresses.