Internet Growth (1981-1991)
RFC 1296

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Network Working Group                                          M. Lottor
Request for Comments: 1296                             SRI International
                                      Network Information Systems Center
                                                            January 1992

                      Internet Growth (1981-1991)

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is
   unlimited.

Abstract

   This document illustrates the growth of the Internet by examination
   of entries in the Domain Name System (DNS) and pre-DNS host tables.
   DNS entries are collected by a program called ZONE, which searches
   the Internet and retrieves data from all known domains.  Pre-DNS host
   table data were retrieved from system archive tapes.  Various
   statistics are presented on the number of hosts and domains.

Table of Contents

   Introduction....................................................   1
   How ZONE Works..................................................   2
   Problems with Data Collection...................................   3
   Scope of the Study..............................................   3
   N. Results......................................................   4
   N.1 Number of Internet Hosts....................................   4
   N.2 Number of Domains...........................................   6
   N.3 Distribution of IP Addresses per Host.......................   7
   N.4 Distribution of Hosts by Top-level Domain...................   7
   N.5 Distribution of Hosts by Host Name..........................   8
   Future Issues...................................................   8
   RFC References..................................................   9
   Security Considerations.........................................   9
   Author's Address................................................   9

Introduction

   This document provides statistics on the growth of the Internet by
   examining the number of Internet hosts and domains over a 10-year
   period.  Before the Domain Name System was established, practically
   all hosts on the Internet were registered with the Network
   Information Center (SRI-NIC) and entries were placed in the Official
   Host Table for each one.  Data on the number of hosts for pre-DNS

Lottor                                                          [Page 1]
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