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OARC's DNS don't-probe list


Please Note: As of February 2021 Don't Probe is a deprecated unsupported service and will be migrated to another vendor.  Watch this space.

OARC maintains a database of IP address space that should not be probed with DNS messages. An address or network may be listed in the database because it is known to be "dark" (such as RFC 1918 space, or certain large blocks held by the U.S. Department of Defense), or due to an abuse complaint where someone specifically requests no further probing of their network. The primary table contains six fields:

  1. Address
  2. Hostname
  3. Added
  4. Comment
  5. Category-ID
  6. Source-ID

Address is an IP address or CIDR netblock such as or Hostname is an optional field. Hostnames in the database are periodically resolved and the answers compared to the Address field. If the address for a hostname changes, the Address field is updated. Thus, Hostname takes a higher precedence than Address. Added is the date and time when the entry was made. Comment should contain a contact email address whenever possible, or at least a company name. Category-ID is an index into the Category table. Source-ID is an index into the Source table (i.e., the person responsible for making this entry).


The following categories are currently defined:

 cid |       category       
   0 | Unknown
   1 | User/admin complaint
   2 | RFC 1918
   3 | Bogon
   4 | Military/Government
   5 | Hoarder
   6 | Exchange Point
   7 | Academia

In order to be assigned the complaint category, the entry must have been made in response to an abuse complaint or specific request from someone responsible for the corresponding address space. Hoarder refers to early recipients of large address space blocks that are known to be unreachable from the public Internet.

Accessing the Database

The database may be accessed via an SSL-encrypted connection to DNS-OARC's secure website for don't-probe. OARC also maintains and provides a Perl script that can output the database entries in various formats such as plain text and FreeBSD ipfw commands. Please contact Admin for access to the database and tools.