RFC 1296 (rfc1296) - Page 2 of 9

Internet Growth (1981-1991)

RFC 1296              Internet Growth (1981-1991)           January 1992


   years comes from copies of the host table at selected times.  The DNS
   system was introduced around 1984 but took almost 4 years before it
   was fully implemented on the Internet.  However, by this time many
   hosts were no longer registered in the Host Table.

   In 1986, the ZONE (Zealot Of Name Edification) program was written.
   ZONE was originally intended to be used during the host-table-to-DNS
   transition period.  ZONE would "walk" the DNS tree and build a host
   table of all the information it collected.  This host table could
   then be used by sites that had not yet made the DNS transition.
   However, ZONE was never used for this purpose.  Instead, it was found
   to be useful for collecting statistics on the size of the domain
   system and the Internet.

   ZONE could not collect complete data on the DNS until around 1988,
   because early versions of BIND (the popular Unix DNS implementation)
   had major problems with the zone transfer function of the DNS
   protocol.  ZONE has been used in varying ways ever since to collect
   this information.  In the first few years, it was used to produce a
   wall-size chart of the domain tree.  However, the number of domains
   quickly outgrew the size of the wall and the charts were abandoned.
   In later years, statistics on the number of hosts and domains were
   extracted from the resulting host table, sometimes categorizing data
   based on top-level domain names or on computer system type or
   manufacturer.

   The time to gather the data also grew from hours to a week, and the
   size of the host table produced soon reached 50 megabytes.  In order
   to reduce the amount of data collected, ZONE is now run in a mode
   collecting only host names and IP addresses, ignoring protocol, host
   information and MX record data.  The host table is then groveled over
   by some utilities (such as sort, uniq and grep) to produce the
   statistics required.  ZONE is currently run every 3 months at SRI.

How ZONE Works

   ZONE maintains a list of domains and their servers and a flag
   indicating whether information for a domain has been successfully
   loaded from one of the servers. Because of another bug in BIND, ZONE
   must be primed with a list of all the top-level domains and their
   name servers.  It then cycles through the domain list, attempting to
   contact one of the servers for each domain not yet transferred.  When
   a server is contacted (via TCP), a Start of Authority (SOA) query is
   first sent to make sure the server is authoritative for the domain
   being requested.  If so, then a zone transfer query (AXFR) is sent to
   request all the resource records for the domain to be retrieved.

   When a name server record (NS) is received, the referenced domain and



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