RFC 1713 (rfc1713) - Page 2 of 13


Tools for DNS debugging



Alternative Format: Original Text Document



RFC 1713                Tools for DNS debugging            November 1994


   On the other hand, many inconsistencies arise from this distributed
   nature: many administrators make mistakes in the way they configure
   their domains and when they delegate authority to sub-domains; many
   of them don't even know how to do these things properly, letting
   problems last and propagate.  Also, many problems occur due to bad
   implementations of both DNS clients and servers, especially very old
   ones, either by not following the standards or by being error prone,
   creating or allowing many of the above problems to happen.

   All these anomalies make DNS less efficient than it could be, causing
   trouble to network operations, thus affecting the overall Internet.
   This document tries to show how important it is to have DNS properly
   managed, including what is already in place to help administrators
   taking better care of their domains.

2. DNS debugging

   To help finding problems in DNS configurations and/or implementations
   there is a set of tools developed specifically for this purpose.
   There is probably a lot of people in charge of domain administration
   having no idea of these tools (and, worse, not aware of the anomalies
   that may exist in their configurations).  What follows is a
   description of some of these programs, their scope, motivations and
   availability, and is hoped to serve as an introduction to the subject
   of DNS debugging, as well as a guide to those who are looking for
   something to help them finding out how healthy their domains and
   servers are.

   Some prior knowledge from the reader is assumed, both on DNS basics
   and some other tools (e.g., dig and nslookup), which are not analyzed
   in detail here; hopefully they are well-known enough from daily
   usage.

2.1. Host

   Host is a program used to retrieve DNS information from name servers.
   This information may be used simply to get simple things like
   address-to-name mapping, or some more advanced purposes, e.g.,
   performing sanity checks on the data.  It was created at Rutgers
   University, but then Eric Wassenaar from Nikhef did a major rewrite
   and still seems to be actively working on improving it.  The program
   is available from ftp://ftp.nikhef.nl/pub/network/host_YYMMDD.tar.Z
   (YYMMDD is the date of the latest release).

   By default, host just maps host names to Internet addresses, querying
   the default servers or some specific one.  It is possible, though, to
   get any kind of data (resource records) by specifying different query
   types and classes and asking for verbose or debugging output, from



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