denic.de DNSSEC Outage: 2018-10-12

Date: October 12, 2018

Overview

This page gives some details on the denic.de DNSSEC outage on October 12, 2018.

Timeline / DNSViz

DNSSEC Debugger

Unlike DNSViz, Verisign's DNSSEC Debugger doesn't archive results, so here's a screenshot of my web browser's output from October 12, 2018.

October 12, 2018 denic.de DNSSEC outage

Google Public DNS: 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. With DNSSEC, DNS queries result in SERVFAIL:

$ dig +dnssec a www.denic.de. @8.8.8.8

; <<>> DiG 9.4.2-P2 <<>> +dnssec a www.denic.de. @8.8.8.8
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 1271
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 512
;; QUESTION SECTION:
;www.denic.de. IN A

;; Query time: 293 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Fri Oct 12 09:02:33 2018
;; MSG SIZE rcvd: 41

You have to disable DNSSEC to make DNS queries work:

$ dig +cd a www.denic.de. @8.8.8.8

; <<>> DiG 9.4.2-P2 <<>> +cd a www.denic.de. @8.8.8.8
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9116
;; flags: qr rd ra cd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.denic.de. IN A

;; ANSWER SECTION:
www.denic.de. 3478 IN A 81.91.170.12

;; Query time: 8 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Fri Oct 12 09:02:33 2018
;; MSG SIZE rcvd: 46

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: denic.de.
[B] denic.de. 3600 IN DNSKEY 257 3 8 ;{id = 26155 (ksk), size = 1536b}
[B] denic.de. 3600 IN A 81.91.170.12
;; Error: No keys with the keytag and algorithm from the RRSIG found
;;[S] self sig OK; [B] bogus; [T] trusted

Twitter

This DNSSEC outage was discussed on Twitter.

denic.de DNSSEC outage Twitter discussion

Logfile examples