RFC 1537 (rfc1537) - Page 1 of 9

Common DNS Data File Configuration Errors

Network Working Group                                        P. Beertema
Request for Comments: 1537                                           CWI
Category: Informational                                     October 1993


               Common DNS Data File Configuration Errors

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 memo describes errors often found in DNS data files. It points
   out common mistakes system administrators tend to make and why they
   often go unnoticed for long periods of time.

Introduction

   Due to the lack of extensive documentation and automated tools, DNS
   zone files have mostly been configured by system administrators, by
   hand. Some of the rules for writing the data files are rather subtle
   and a few common mistakes are seen in domains worldwide.

   This document is an attempt to list "surprises" that administrators
   might find hidden in their zone files. It describes the symptoms of
   the malady and prescribes medicine to cure that. It also gives some
   general recommendations and advice on specific nameserver and zone
   file issues and on the (proper) use of the Domain Name System.

1. SOA records

   A problem I've found in quite some nameservers is that the various
   timers have been set (far) too low. Especially for top level domain
   nameservers this causes unnecessary traffic over international and
   intercontinental links.

   Unfortunately the examples given in the BIND manual, in RFC's and in
   some expert documents give those very short timer values, and that's
   most likely what people have modeled their SOA records after.

   First of all a short explanation of the timers used in the SOA
   record:






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