Do A records affect email deliverability?

Yes. If your SPF record uses the 'a' mechanism, your domain's A record must resolve to your mail server's IP. Mail servers also do forward-confirmed reverse DNS checks: your sending IP's PTR record should resolve to a hostname, and that hostname's A record should point back to the same IP.

A Record Lookup - Check DNS A and AAAA Records

Q: What is a DNS A record?

A DNS A record maps a domain name to an IPv4 address. When someone visits your website or connects to your mail server, their computer performs an A record lookup to find the IP address. AAAA records do the same for IPv6 addresses.

Q: What is the difference between an A record and a CNAME record?

An A record points directly to an IP address. A CNAME points to another hostname which then resolves to an IP. You cannot use a CNAME at the root of a domain - you must use an A record there.

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Look up the IPv4 (A) and IPv6 (AAAA) records for any domain. Verify your domain points to the right server, diagnose missing records after a migration, and confirm DNS changes have propagated.

What is a DNS A record?

A DNS A record (Address record) maps a domain name to an IPv4 address - the 32-bit numeric address that identifies a server on the internet, for example 93.184.216.34. When someone visits your website or connects to your mail server, their computer performs an A record lookup to find the IP address behind the domain name.

AAAA records (quad-A) do the same thing for IPv6 addresses - the newer 128-bit format like 2606:2800:220:1:248:1893:25c8:1946. Many servers have both A and AAAA records, letting clients connect over whichever protocol they support.

When to use an A record lookup

After a server migration or hosting change
Confirm your domain now points to the new server's IP address and the old IP is no longer in DNS.
Diagnosing a website that is not loading
Check whether the A record is missing, points to the wrong IP, or has not propagated yet.
Verifying SPF record accuracy
If your SPF record uses the a mechanism, check the A record to confirm which IP it authorizes to send email.
Checking subdomain routing
Confirm that mail.yourdomain.com or smtp.yourdomain.com resolve to the right server.

A records and email deliverability

A records affect email in two ways. First, if your SPF record uses the a mechanism, the A record of your domain must resolve to your mail server's IP. Second, mail servers often do a forward-confirmed reverse DNS check: the PTR record of your sending IP should resolve to a hostname, and that hostname's A record should point back to the same IP. If this does not match, some mail servers will score your email negatively.

Use the Reverse DNS Lookup tool to check PTR records, and the SPF Lookup to verify your SPF record is correctly configured.

What does TTL mean?

TTL (Time to Live) is how long DNS resolvers and browsers cache the record before checking again, measured in seconds. A TTL of 300 means the record is cached for 5 minutes. A TTL of 3600 means 1 hour.

Before changing a server's IP, lower the TTL to 300 seconds a day in advance so that DNS propagates quickly after the change. Once the migration is confirmed, raise the TTL back to a higher value like 3600 or 86400 to reduce DNS query load.

FAQ

How many A records can a domain have?

A domain can have multiple A records pointing to different IP addresses, which is used for basic round-robin load balancing. However, most small business websites and mail servers have a single A record. Multiple A records for the same hostname are valid but require consistent configuration across all IPs.

What is the difference between an A record and a CNAME record?

An A record points directly to an IP address. A CNAME (Canonical Name) record points to another hostname, which then resolves to an IP. You cannot use a CNAME at the root of a domain (apex/naked domain) - you must use an A record there. Use the CNAME Lookup to check CNAME records.

My domain has an A record but the site is not loading

Check that the IP in the A record is correct and that the server at that IP is reachable. DNS propagation takes a few minutes to hours depending on TTL. If the record is recent, wait and check again. If the A record is correct but something is still wrong, the issue is likely at the server level (firewall, web server config), not DNS.

Why does my domain have no AAAA record?

AAAA records require IPv6 support from your hosting provider. Many shared hosting environments only assign IPv4 addresses, so having no AAAA record is common and not a problem. Most email and web traffic still works fine over IPv4 only.