What is the APL record format?

APL records use the format: address_family:prefix. For IPv4, use 1: (e.g., 1:192.0.2.0/24). For IPv6, use 2: (e.g., 2:2001:db8::/32). Prefix with ! for exclusion (e.g., !1:10.0.0.0/8).

Why are APL records rarely used?

APL records are experimental (RFC 3123), have limited resolver and application support, and most use cases are better served by alternatives like SPF for email or firewall rules for access control.

What's the difference between APL and SPF records?

APL is a general-purpose experimental record for address lists. SPF (stored in TXT records) is a widely-adopted standard specifically for email sender authorization. SPF has much broader support and deployment.

APL Record Experimental

Q: What is an APL record?

An APL record (Address Prefix List, RFC 3123) stores lists of IP address prefixes in DNS using CIDR notation. It's an experimental record type that can include or exclude IPv4 and IPv6 address ranges.

The APL record (Address Prefix List) stores lists of address ranges (prefixes) in DNS. Defined in RFC 3123, it was designed to specify which IP address ranges are associated with a domain. APL is an experimental record type with limited deployment.

Limited Use

APL records are experimental (RFC 3123) and rarely used in practice. Most use cases are better served by other mechanisms like SPF or firewall rules.

Look Up APL Records

Check APL records for any domain using our free DNS lookup tool.

Look Up APL Records →

What Is an APL Record?

APL records allow storing lists of IP address prefixes (CIDR notation) associated with a domain name. Each entry can be marked as inclusive or exclusive:

Address prefixes — Store CIDR blocks (e.g., 192.0.2.0/24)
Include/exclude — Mark addresses as included or negated
IPv4 and IPv6 — Supports both address families
Multiple prefixes — Single record can hold many ranges

APL Record Format

Example APL Record

example.com.    3600    IN    APL    1:192.0.2.0/24 2:2001:db8::/32 !1:10.0.0.0/8

Includes 192.0.2.0/24 and 2001:db8::/32, excludes 10.0.0.0/8.

APL Record Syntax

Component	Description	Example
Address Family	1 = IPv4, 2 = IPv6	1: or 2:
Prefix	IP address/prefix length	192.0.2.0/24
Negation	! prefix means exclude	!1:10.0.0.0/8

Address Family Numbers

Number	Address Family
1	IPv4
2	IPv6

APL Examples

Single IPv4 Prefix

example.com.    APL    1:192.0.2.0/24

Multiple Prefixes

example.com.    APL    1:192.0.2.0/24 1:198.51.100.0/24 2:2001:db8::/32

With Exclusions

; Include 192.0.2.0/24 but exclude 192.0.2.128/25
example.com.    APL    1:192.0.2.0/24 !1:192.0.2.128/25

IPv6 Only

example.com.    APL    2:2001:db8::/32 2:2001:db8:1::/48

Potential Use Cases

While rarely deployed, APL records could theoretically be used for:

Network documentation — Document allocated address ranges
Access control lists — Define allowed/denied networks
Geographic mapping — Associate regions with IP ranges
SPF-like mechanisms — Define authorized senders (though SPF is preferred)

Why APL Is Rarely Used

Experimental status — RFC 3123 is experimental, not standards track
Limited resolver support — Many resolvers don't handle APL
Better alternatives exist — SPF for email, firewall rules for access control
Application support — Few applications query or use APL records
No clear use case — No compelling reason to use over alternatives

APL vs SPF

Aspect	APL Record	SPF (TXT Record)
Purpose	General address lists	Email sender authorization
Format	CIDR notation with AFI	Flexible syntax
Adoption	Very rare	Widespread
Status	Experimental	Proposed Standard

Querying APL Records

# Using dig
dig example.com APL

# Using drill
drill example.com APL

Troubleshooting APL

Common issues and solutions:

Record not found — APL records are very rare; most domains don't have them.
Resolver issues — Some resolvers may not properly handle APL type.
Syntax errors — Ensure address family prefix and CIDR notation are correct.

Check APL Records

Use our DNS Record Finder to look up APL records for any domain.