What is the significance of a DNS A record?

The letter “A” signifies “address,” representing the foundational type of DNS record. It reveals the IP address associated with a specific domain. To illustrate, if you query the DNS records of toffstech.com, the current A record provides the IP address: 104.17.210.9.

A records exclusively accommodate IPv4 addresses. If a website utilizes an IPv6 address, it opts for an “AAAA” record.

Here’s a sample A record:

• Domain: example.com
• Record Type: A
• Value: 192.0.2.1
• TTL: 14400

In this instance, the “@” symbol designates a record for the root domain, and the “14400” value denotes TTL (time to live), measured in seconds. The default TTL for A records stands at 14,400 seconds. This implies that when an A record is modified, it requires 240 minutes (14,400 seconds) to become effective.

While most websites have a single A record, multiple A records are plausible. Prominent websites might feature multiple A records as part of round-robin load balancing. This technique evenly distributes request traffic across various IP addresses, each hosting identical content.

When are DNS A records utilized?

The primary application of A records involves IP address lookups, where they facilitate the mapping of a domain name (e.g., “toffstech.com”) to an IPv4 address. This functionality allows a user’s device to establish a connection with and load a website, all without requiring the user to commit the actual IP address to memory and type it in manually. This process is automated by the user’s web browser, which initiates a query to a DNS resolver.

Additionally, DNS A records find utility in supporting Domain Name System-based Blackhole Lists (DNSBLs). These lists aid mail servers in recognizing and obstructing email messages originating from domains associated with known spammers.

For those interested in delving deeper into DNS A records, the original 1987 RFC that defines A records along with various other DNS record types can be explored at this source.