ip6.arpa DNSSEC Outage: 2017-10-24

Date: October 24, 2017

Overview

This page gives some details on the ip6.arpa DNSSEC outage on October 24, 2017.

Timeline / DNSViz

Zonemaster

DNS OARC: with and without DNSSEC

DNSSEC can be disabled in queries via the CD (checking disabled) bit. Let's compare DNS queries with and without DNSSEC.

$ dig +dnssec ns ip6.arpa. @184.105.193.74

; <<>> DiG 9.4.2-P2 <<>> +dnssec ns ip6.arpa. @184.105.193.74
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 29848
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
;; QUESTION SECTION:
;ip6.arpa. IN NS

;; Query time: 1662 msec
;; SERVER: 184.105.193.74#53(184.105.193.74)
;; WHEN: Tue Oct 24 21:04:41 2017
;; MSG SIZE rcvd: 37

You have to disable DNSSEC to make DNS queries work:

$ dig +cd ns ip6.arpa. @184.105.193.74

; <<>> DiG 9.4.2-P2 <<>> +cd ns ip6.arpa. @184.105.193.74
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29204
;; flags: qr rd ra cd; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;ip6.arpa. IN NS

;; ANSWER SECTION:
ip6.arpa. 3598 IN NS a.ip6-servers.arpa.
ip6.arpa. 3598 IN NS b.ip6-servers.arpa.
ip6.arpa. 3598 IN NS c.ip6-servers.arpa.
ip6.arpa. 3598 IN NS d.ip6-servers.arpa.
ip6.arpa. 3598 IN NS e.ip6-servers.arpa.
ip6.arpa. 3598 IN NS f.ip6-servers.arpa.

;; Query time: 482 msec
;; SERVER: 184.105.193.74#53(184.105.193.74)
;; WHEN: Tue Oct 24 21:04:42 2017
;; MSG SIZE rcvd: 134

drill trace

Since DNSSEC contains so much garbage, I put the complete drill trace into its own file with the relevant portion below (emphasis added):

;; Domain: ip6.arpa.
;; Signature ok but no chain to a trusted key or ds record
[S] ip6.arpa. 3600 IN DNSKEY 256 3 8 ;{id = 19561 (zsk), size = 1024b}
ip6.arpa. 3600 IN DNSKEY 257 3 8 ;{id = 52682 (ksk), size = 2048b}
[S] Existence denied: ip6.arpa. A
;;[S] self sig OK; [B] bogus; [T] trusted

Logfile examples