How the RIPE NCC Service Region Hostcount is Performed

The Hostcount is run at the end of each calendar month. The DNS query tool "host", written by the late Eric Wassenaar at NIKHEF, is used.

The Hostcount uses the following process:

• Third parties collect local data
• RIPE NCC collects the remaining data
• Data is combined and published

Third Parties Collect Local Data

The Hostcount is more accurate and more data is collected when a 'local' machine collects the data. This usually means a machine that is geographically situated in the country that the TLD represents. The main reasons for this are:

• Connectivity external to the geographic region has no influence on the data collection
• The organisation collecting the data, specifically the IP address range of their network, is usually 'well-known' in the area and therefore more trusted. This means that [zone transfers] are refused less often, so that more data is found.

Because of the increased accuracy of third party data, we prefer that the data collection is done by a local site wherever possible, usually a Network Information Centre (NIC), University or similar institution.

To collect the data, each local organisation runs the host tool on their TLD code. host acts conceptually as follows

1. Zone transfer the Top-Level Domain.
   This means: ask one of the nameservers for the TLD to give out everything in its zone file for that TLD.
2. Remember any Nameserver records that are seen.
   Namserver records indicate the existence of a sub-zone and tell us which nameservers should know something about the sub-zone.
3. Zone transfer all of the sub-zones.
4. Remember any Nameserver records that are seen.
5. Are there any more subzones ?
   • ? Yes ? Go to step 3.
   • ? No ? Stop.

The RIPE NCC Collects Remaining Data

For all of the TLDs served by the RIPE NCC that do not have a local data collector, the RIPE NCC collects the data from its site in Amsterdam. The method used is the same as for the local data as described above.

Data Combined and Published

The RIPE NCC collects the files from the sites of the local collectors using FTP. Once a complete set of files is gathered, the data is analysed and summary statistics are published.