Complete List of Class A and Class B Networks

This list is not unique--there are other lists of Internet IP networks on the Web (1), but this particular list has the advantage that it is reasonably current, includes both Class A and Class B networks, has contact information on the various networks, and also offers a downloadable list suitable for further data analysis.

Now, this information is of course readily available through the whois service at the three regional Internet registries (ARIN, RIPE, and APNIC), but this does not allow you to perform, say, statistical analysis on the data, as records are retrieved one-at-a-time.

To get an overall view of the IPv4 address space, I went ahead and compiled a list of all Class A and Class B networks for the enjoyment of the interested public. This list was compiled by querying the ARIN database for all Class A- and Class B records, with additional information taken from RIPE and APNIC if a corresponding reference was returned by ARIN.

The data was then put into a form suitable to be displayed in a table using custom built Perl scripts. The data was retrieved from the registry databases on Sept 3, 1999, and the final version of the Network Tables was uploaded onto this server on Sept 19, 1999.

For simplicity, we assume the classic subdivision into A, B, etc. network classes. No effort was made to accomodate more recent developments, such as CIDR (Classless Inter-Domain Routing).

Feedback and suggestions are highly encouraged. Please contact me at

List of Class A Networks *:


List of Class B Networks *:


Downloadable List

Click here to download a complete list of all Class A and Class B networks. This is a pipe-separated file suitable for importing into a spreadsheet- or database program. Size: 400KB (ZIPped), 1.4MB (extracted).
(*): Note that all pages have a size of about 200KB. Depending on the performance of your Operating Environment and the Browser you are using, it may take a while to render the tables.
An entry no match in the table means that the network is available.

(1): See for instance This site also presents a conceptual overview of the complete IPv4 address space.
Dragonstar has a list that includes Classes A, B and C, but is not always current, and some ranges are better covered than others.

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(c) Adrian Turtschi, Sept 13, 1999