Domain Security Info

IP Prefixes

Updated May 1, 2026, 8:29 AM

Managing IP prefixes#

IP prefixes let you associate IP address ranges with brands. When a user looks up an IP address that falls within a known prefix, the tool displays the associated brand badge.

What is an IP prefix?#

An IP prefix is a range of IP addresses written in CIDR notation. CIDR notation combines an IP address with a prefix length to define a block of addresses.

Examples:

CIDRWhat it covers
8.8.8.0/24256 addresses from 8.8.8.0 to 8.8.8.255
8.8.8.8/32A single address: 8.8.8.8
2001:4860:4860::/48A large block of IPv6 addresses

IP prefix fields#

FieldRequiredDescription
IP networkYesThe IP prefix in CIDR notation (for example, 8.8.8.0/24 or 2001:db8::/32). Must be unique.
IP versionAutoAutomatically detected as 4 (IPv4) or 6 (IPv6) based on the address format.
BrandYesThe brand that owns this IP range. Select from the existing brands list.
DescriptionNoA note about what this prefix is used for (for example, "Google Public DNS" or "AWS US-East-1").
SourceNoWhere this prefix information came from (for example, "manual", "import", "ARIN records").
VerifiedNoWhether this prefix has been independently verified.

How IP prefix matching works#

When a user looks up an IP address:

  1. The tool determines whether it's IPv4 or IPv6.
  2. It fetches all known prefixes for that IP version from the database.
  3. It tests the IP address against each prefix using bitwise comparison.
  4. If multiple prefixes match, it returns the most specific one (the one with the longest prefix length).

Most-specific-first matching#

The most important concept in IP prefix matching is that more specific prefixes take priority over broader ones.

Example: Your database has these prefixes for Google:

PrefixSizeDescription
8.8.8.0/24256 addressesGoogle DNS range
8.8.8.0/2816 addressesGoogle DNS primary
8.8.8.8/321 addressGoogle Public DNS resolver

When a user looks up 8.8.8.8:

  • All three prefixes match.
  • The tool returns 8.8.8.8/32 because /32 is the most specific (covers just one address).

When a user looks up 8.8.8.5:

  • Only /24 and /28 match.
  • The tool returns 8.8.8.0/28 because /28 is more specific than /24.

When a user looks up 8.8.8.200:

  • Only /24 matches.
  • The tool returns 8.8.8.0/24.

Creating an IP prefix#

  1. Go to IP Prefixes in the navigation.
  2. Click Add IP Prefix.
  3. Enter the IP network in CIDR notation (for example, 203.0.113.0/24).
  4. Select a brand from the dropdown.
  5. Add a description (optional but recommended).
  6. Add the source of this information (optional).
  7. Set the verified flag if you've confirmed this information.
  8. Click Save.

Tips for CIDR notation#

  • IPv4 format: x.x.x.x/prefix where prefix is 0โ€“32. Example: 192.168.1.0/24
  • IPv6 format: xxxx:xxxx:xxxx::/prefix where prefix is 0โ€“128. Example: 2001:db8::/32
  • The prefix length determines the size of the block. Larger prefix numbers mean smaller, more specific blocks.
  • The network address should be the base of the block. For a /24, use .0 as the last octet (for example, 8.8.8.0/24, not 8.8.8.5/24).
  • A /32 represents a single IPv4 address. Use this for individual servers or resolvers.
  • A /128 represents a single IPv6 address.

Tips for organizing prefixes#

  • Start broad, then add specific. Add the organization's main allocation (like /16 or /24) first, then add more specific blocks if needed.
  • Use descriptions to explain what each prefix is used for. This helps other admins understand the data.
  • Group by brand to see all of an organization's IP space together.
  • Verify with authoritative sources like ARIN, RIPE, or the organization's published IP ranges.

Editing an IP prefix#

  1. Go to IP Prefixes in the navigation.
  2. Find the prefix in the list.
  3. Click Edit in the Actions column.
  4. Update the fields you want to change.
  5. Click Save.

Deleting an IP prefix#

  1. Go to IP Prefixes in the navigation.
  2. Find the prefix in the list.
  3. Click Delete in the Actions column.
  4. Confirm the deletion.

Searching IP prefixes#

You can search and filter by:

  • IP address or prefix โ€” Partial matches work.
  • Brand โ€” Filter to show only prefixes for a specific brand.
  • Source โ€” Filter by data source.
  • Verified status โ€” Show only verified or unverified prefixes.

IPv4 vs. IPv6#

The tool supports both IPv4 and IPv6 prefixes. The IP version is automatically detected from the address format:

FormatVersion
203.0.113.0/24IPv4
2001:db8::/32IPv6

IPv4 matching uses 32-bit integer comparison with subnet masking. IPv6 matching uses 128-bit binary string comparison. Both use the same most-specific-first logic.

How IP prefixes affect lookups#

When a user looks up an IP address:

  1. The tool checks the IP against all known prefixes for the matching IP version.
  2. If a match is found, the associated brand badge appears in the results.
  3. The brand information supplements the WHOIS data โ€” WHOIS shows the official registration, while the brand badge shows additional context from the admin database.
  4. If no prefix matches, the IP results show only WHOIS data without a brand badge.