A Common Operational Problem in DNS Servers - Failure To Communicate.
draft-ietf-dnsop-no-response-issue-14

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Network Working Group                                         M. Andrews
Internet-Draft                                                 R. Bellis
Intended status: Best Current Practice                               ISC
Expires: May 7, 2020                                    November 4, 2019

 A Common Operational Problem in DNS Servers - Failure To Communicate.
                 draft-ietf-dnsop-no-response-issue-14

Abstract

   The DNS is a query / response protocol.  Failing to respond to
   queries, or responding incorrectly, causes both immediate operational
   problems and long term problems with protocol development.

   This document identifies a number of common kinds of queries to which
   some servers either fail to respond or else respond incorrectly.
   This document also suggests procedures for zone operators to apply to
   identify and remediate the problem.

   The document does not look at the DNS data itself, just the structure
   of the responses.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 7, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of

Andrews & Bellis           Expires May 7, 2020                  [Page 1]
Internet-Draft           Failure To Communicate            November 2019

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Consequences  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Common kinds of queries that result in no or bad responses. .   5
     3.1.  Basic DNS Queries . . . . . . . . . . . . . . . . . . . .   5
       3.1.1.  Zone Existence  . . . . . . . . . . . . . . . . . . .   5
       3.1.2.  Unknown / Unsupported Type Queries  . . . . . . . . .   5
       3.1.3.  DNS Flags . . . . . . . . . . . . . . . . . . . . . .   6
       3.1.4.  Unknown DNS opcodes . . . . . . . . . . . . . . . . .   6
       3.1.5.  TCP Queries . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  EDNS Queries  . . . . . . . . . . . . . . . . . . . . . .   6
       3.2.1.  EDNS Queries - Version Independent  . . . . . . . . .   7
       3.2.2.  EDNS Queries - Version Specific . . . . . . . . . . .   7
       3.2.3.  EDNS Options  . . . . . . . . . . . . . . . . . . . .   7
       3.2.4.  EDNS Flags  . . . . . . . . . . . . . . . . . . . . .   7
       3.2.5.  Truncated EDNS Responses  . . . . . . . . . . . . . .   8
       3.2.6.  DO=1 Handling . . . . . . . . . . . . . . . . . . . .   8
       3.2.7.  EDNS over TCP . . . . . . . . . . . . . . . . . . . .   8
   4.  Firewalls and Load Balancers  . . . . . . . . . . . . . . . .   8
   5.  Scrubbing Services  . . . . . . . . . . . . . . . . . . . . .   9
   6.  Whole Answer Caches . . . . . . . . . . . . . . . . . . . . .  10
   7.  Response Code Selection . . . . . . . . . . . . . . . . . . .  10
   8.  Testing . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     8.1.  Testing - Basic DNS . . . . . . . . . . . . . . . . . . .  11
       8.1.1.  Is The Server Configured For The Zone?  . . . . . . .  11
       8.1.2.  Testing Unknown Types . . . . . . . . . . . . . . . .  12
       8.1.3.  Testing Header Bits . . . . . . . . . . . . . . . . .  12
       8.1.4.  Testing Unknown Opcodes . . . . . . . . . . . . . . .  14
       8.1.5.  Testing TCP . . . . . . . . . . . . . . . . . . . . .  15
     8.2.  Testing - Extended DNS  . . . . . . . . . . . . . . . . .  15
       8.2.1.  Testing Minimal EDNS  . . . . . . . . . . . . . . . .  16
       8.2.2.  Testing EDNS Version Negotiation  . . . . . . . . . .  16
       8.2.3.  Testing Unknown EDNS Options  . . . . . . . . . . . .  17
       8.2.4.  Testing Unknown EDNS Flags  . . . . . . . . . . . . .  18
       8.2.5.  Testing EDNS Version Negotiation With Unknown EDNS