How do MX record priority numbers work?

Lower numbers have higher priority. For example, a mail server with priority 10 will always receive emails before a backup server with priority 20.

Can an MX record point directly to an IP address?

No. RFC 5321 strictly forbids IP addresses in MX records; an MX record must always specify a valid domain hostname (FQDN) that has an A or AAAA record.

How do I check my domain's MX records?

Enter your domain into LotsofNetwork's DNS Lookup tool or run 'dig MX example.com' in terminal.

Home/DNS Lookup/MX Record

CNAME TXT

DNS Resource Record Type

MX Record: Mail Exchange Record

Directs incoming email traffic to designated mail servers with configurable priority weights.

Record Type

Query Protocol

DNS Port 53

Standard / RFC

RFC 1035 & RFC 5321

Recommended TTL

3600 seconds

Query Live MX Records

Query any domain name to inspect authoritative MX records, response latency, and TTL values.

Loading DNS lookup tool...

BIND Zone File Syntax

Standard BIND representation of this record in authoritative master zone files:

example.com. 3600 IN MX 10 mail.example.com.

Recommended TTL: 3600 seconds (1 hour) to 86400 seconds (24 hours) for stable email routing.

Common Configuration Pitfalls

Pointing an MX record directly to an IP address instead of a valid hostname (FQDN), which violates RFC 5321.
Pointing an MX record to a CNAME alias instead of a direct A/AAAA hostname.
Forgetting to update SPF records when modifying MX records.

How the MX Record Operates in DNS Resolution

The MX (Mail Exchange) record specifies which mail servers are authorized to accept incoming emails on behalf of a domain. MX records include a preference number (priority weight) indicating server order: mail transfer agents will always try the server with the lowest numerical preference first, falling back to higher numbers if the primary is unreachable.