A Record (Address Record)

What is an A Record?

An A record (Address Record) is a fundamental DNS record type that maps a domain name to an IPv4 address. When someone types your domain into their browser, DNS servers use A records to find the IP address of the server hosting your website.

How A Records Work

When a user visits example.com:

1. DNS Query: Browser asks "What's the IP for example.com?"

2. A Record Lookup: DNS servers find the A record

3. IP Returned: The IPv4 address (e.g., 93.184.216.34) is returned

4. Connection Made: Browser connects to the IP address

example.com.    IN    A    93.184.216.34

This DNS record format shows:

• example.com. - The domain (trailing dot indicates root)
• IN - Internet class
• A - Record type
• 93.184.216.34 - The IPv4 address

A Record Configuration

Basic Setup

Most domain configurations need at minimum:

@       IN    A    203.0.113.50    ; Root domain
www     IN    A    203.0.113.50    ; www subdomain

The "@" symbol represents the root domain (example.com without www).

Multiple A Records

A domain can have multiple A records for load balancing:

example.com.    IN    A    203.0.113.50
example.com.    IN    A    203.0.113.51
example.com.    IN    A    203.0.113.52

DNS resolvers typically rotate through these addresses (round-robin) or select based on geography.

TTL (Time To Live)

A records include a TTL value specifying how long resolvers should cache the record:

example.com.    300    IN    A    203.0.113.50

A 300-second (5-minute) TTL means DNS changes propagate within 5 minutes. Lower TTLs enable faster changes but increase DNS query volume.

Common A Record Use Cases

Web Hosting

Point your domain to your web server:

@ → Your server's IPv4 address
www → Your server's IPv4 address (or use CNAME)

Subdomains

Create A records for different services:

api.example.com     → API server IP
blog.example.com    → Blog server IP
shop.example.com    → E-commerce server IP

CDN Configuration

Some CDNs require A records pointing to their edge IPs (though CNAME is more common):

example.com    → CDN edge IP

A Record vs Other Record Types

Checking A Records

dig example.com A

nslookup example.com

curl "https://domscan.net/v1/health?domain=example.com"
# Returns DNS configuration including A records

Best Practices

1. Always set both @ and www: Users type domains both ways

2. Use appropriate TTLs: 300-3600 seconds for most cases; lower before planned changes

3. Consider AAAA records too: IPv6 is increasingly important

4. Monitor records: Incorrect A records mean site downtime

5. Document changes: Keep track of what IP addresses serve what purpose

A records are the foundation of web hosting. Understanding them is essential for any developer managing domain infrastructure.