A Common Operational Problem in DNS Servers - Failure To Respond.
draft-ietf-dnsop-no-response-issue-03
Network Working Group M. Andrews
Internet-Draft ISC
Intended status: Best Current Practice April 6, 2016
Expires: October 8, 2016
A Common Operational Problem in DNS Servers - Failure To Respond.
draft-ietf-dnsop-no-response-issue-03
Abstract
The DNS is a query / response protocol. Failure to respond or to
respond correctly to queries 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 TLD and other similar zone
operators to apply to help reduce / eliminate 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 http://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 October 8, 2016.
Copyright Notice
Copyright (c) 2016 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
(http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Common queries kinds that result in non responses. . . . . . 3
2.1. EDNS Queries - Version Independent . . . . . . . . . . . 3
2.2. EDNS Queries - Version Specific . . . . . . . . . . . . . 4
2.3. EDNS Options . . . . . . . . . . . . . . . . . . . . . . 4
2.4. EDNS Flags . . . . . . . . . . . . . . . . . . . . . . . 4
2.5. DNS Flags . . . . . . . . . . . . . . . . . . . . . . . . 4
2.6. Unknown / Unsupported Type Queries . . . . . . . . . . . 5
2.7. Unknown DNS opcodes . . . . . . . . . . . . . . . . . . . 5
2.8. TCP Queries . . . . . . . . . . . . . . . . . . . . . . . 5
3. Remediating . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Firewalls and Load Balancers . . . . . . . . . . . . . . . . 7
5. Scrubbing Services . . . . . . . . . . . . . . . . . . . . . 8
6. Whole Answer Caches . . . . . . . . . . . . . . . . . . . . . 9
7. Response Code Selection . . . . . . . . . . . . . . . . . . . 9
8. Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Testing - Basic DNS . . . . . . . . . . . . . . . . . . . 10
8.2. Testing - Extended DNS . . . . . . . . . . . . . . . . . 12
9. Security Considerations . . . . . . . . . . . . . . . . . . . 15
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
11. Normative References . . . . . . . . . . . . . . . . . . . . 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
The DNS [RFC1034], [RFC1035] is a query / response protocol. Failure
to respond to queries or to respond incorrectly causes both immediate
operational problems and long term problems with protocol
development.
Failure to respond to a query is indistinguishable from a packet loss
without doing a analysis of query response patterns and results in
unnecessary additional queries being made by DNS clients and
unnecessary delays being introduced to the resolution process.
Due to the inability to distinguish between packet loss and
nameservers dropping EDNS [RFC6891] queries, packet loss is sometimes
misclassified as lack of EDNS support which can lead to DNSSEC
validation failures.
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