.rs TLD DNSSEC Outage: 2019-11-28

Date: November 28, 2019

Overview

This page gives some details on the .rs (Serbia) TLD DNSSEC outage on November 28, 2019.

Timeline / DNSViz

(At the time of this writing, DNSViz historical archives have been down for months. DNSSEC makes its users think downtime doesn't matter.)

DNSSEC Debugger

Here's a screenshot of my web browser's output from November 28, 2019:

November 28, 2019 .rs (Serbia) TLD DNSSEC outage

Google 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.

$ dig +dnssec ns rs. @8.8.8.8

; <<>> DiG 9.4.2-P2 <<>> +dnssec ns rs. @8.8.8.8
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 28332
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 512
;; QUESTION SECTION:
;rs. IN NS

;; Query time: 27 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Thu Nov 28 09:31:28 2019
;; MSG SIZE rcvd: 31

You have to disable DNSSEC to make DNS queries work:

$ dig +cd ns rs. @8.8.8.8

; <<>> DiG 9.4.2-P2 <<>> +cd ns rs. @8.8.8.8
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41856
;; flags: qr rd ra cd; QUERY: 1, ANSWER: 7, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;rs. IN NS

;; ANSWER SECTION:
rs. 3599 IN NS k.nic.rs.
rs. 3599 IN NS g.nic.rs.
rs. 3599 IN NS b.nic.rs.
rs. 3599 IN NS h.nic.rs.
rs. 3599 IN NS a.nic.rs.
rs. 3599 IN NS l.nic.rs.
rs. 3599 IN NS f.nic.rs.

;; Query time: 27 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Thu Nov 28 09:31:28 2019
;; MSG SIZE rcvd: 136

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):

[T] rs. 86400 IN DS 64642 8 2 d76a68b41d96a5dad95216456894e5e539983f39a3df838dd597bdf21c8b8c2b
;; Domain: rs.
;; Signature ok but no chain to a trusted key or ds record
[S] rs. 3600 IN DNSKEY 256 3 8 ;{id = 46599 (zsk), size = 1024b}
rs. 3600 IN DNSKEY 257 3 8 ;{id = 33706 (ksk), size = 2048b}
[S] Existence denied: rs. A
;;[S] self sig OK; [B] bogus; [T] trusted

Logfile examples

These Unbound log entries come from different Unbound instances, each on different servers in different geographical regions.