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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  Name Systems and TCP/IP Name Registration and Name Resolution            9  TCP/IP Name Systems: Host Tables and Domain Name System (DNS)

Overview and History of TCP/IP Host Names and Name Systems 1 2 3 4 TCP/IP Domain Name System (DNS)

Weaknesses of the Host Table Name System

The use of a centralized master file for name registration certainly worked better than using the equivalent of “inter-office memos” to publish host name lists, but was itself only practical in the early days of TCP/IP. As the internetwork grew larger, the weaknesses of the host table system grew:

• Central Administration Overload: The changes to the central file became more frequent, increasing the administrative load on the individual managing the “master” file to the point where changes were being made many times per day. As the Internet continued to grow, it would eventually have been impossible for a human being to enter the changes as fast as they were being submitted.
  
  
• Growth In Size Of the Master File: Every host needed a line in the master file. When the Internet grew to be thousands and eventually millions of devices, the file size would have become excessive.
  
  
• Excessive Bandwidth Use: Since the file was changing so often, this also meant that all the devices on the network had to keep downloading this master file repeatedly to stay current. At the same time, the file was also growing in size as just mentioned. The combination of many downloads of a large file meant large amounts of network bandwidth were being consumed on something that is, in essence, an overhead activity.
  
  
• Flat Namespace Problems: The lack of a hierarchical name space led to conflicts when users chose identical names for their devices, and this further increased the workload on the central administrator. These issues were ameliorated in part by using naming conventions, such as using a prefix with a location before each individual machine name, but this was not an ideal solution.

All of these are reasons why the designers of the Internet eventually moved away from using host tables for the entire Internet to the more capable Domain Name System (DNS).

Overview and History of TCP/IP Host Names and Name Systems 1 2 3 4 TCP/IP Domain Name System (DNS)