Some domain names with ultralow servers (with IPv6) are not being resolved

BigDargon
3 wk ago
1reply

Hi,

Recently, I noticed that ultralow servers with IPv6 (specifically greencloud-sgn) are not resolving some domain names (e.g., grc.com, dnsleaktest.com, etc.). Many people in Vietnam have also complained about this issue. Here are the details:

* Greencloud-sgn (with IPv6):

Output https://dns.nextdns.io/info

{"locationName": "🇻🇳 Ho Chi Minh, Viet Nam", "pop": "greencloud-sgn", "rtt": 7996}

When accessing the domains grc.com and dnsleaktest.com, both result in an ERR_NAME_NOT_RESOLVED error (when using the Edge browser). Other browsers such as Chrome/Firefox also show an error indicating the page cannot be found.

* Lightnode-sgn (IPv4 only):

Output https://dns.nextdns.io/info

{"locationName": "🇻🇳 Ho Chi Minh, Viet Nam", "pop": "lightnode-sgn", "rtt": 95827}

If my browser switches to a different server (without IPv6), both websites are accessible normally.

* Additional information

- I used the DNSSEC checker tool to check the domain name, and the results showed that all authoritative DNS servers responded normally. Therefore, I ruled out the possibility that the authoritative DNS servers were experiencing problems.

- If I check the DNS server from https://browserleaks.com/dns, it only recognizes the IPv6 address of the greencloud-sgn server.

I suspect that the ultralow server is only resolving DNS on IPv6, which is causing this error.

Hopefully NextDNS will check and fix it! Thanks!

BigDargon
2 wk ago
Reported - view

Update: Query using dig. I suspect there was an error during the DNSSEC authentication process with the greencloud-sgn server (which has IPv6).

* greencloud-sgn

No CHAOS, error status SERVFAIL

; <<>> DiG 9.17.15 <<>> grc.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 30952
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;grc.com.                       IN      A

;; Query time: 3013 msec
;; SERVER: 45.90.28.68#53(45.90.28.68) (UDP)
;; WHEN: Tue Feb 10 16:15:45 SE Asia Standard Time 2026
;; MSG SIZE  rcvd: 25


; <<>> DiG 9.17.15 <<>> dnsleaktest.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 14002
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;dnsleaktest.com.               IN      A

;; Query time: 3008 msec
;; SERVER: 45.90.28.68#53(45.90.28.68) (UDP)
;; WHEN: Tue Feb 10 16:16:18 SE Asia Standard Time 2026
;; MSG SIZE  rcvd: 33

With CHAOS output

C:\Users\AMD>dig grc.com CHAOS
;; ;; Question section mismatch: got grc.com/A/IN

; <<>> DiG 9.17.15 <<>> grc.com CHAOS
;; global options: +cmd
;; connection timed out; no servers could be reached

C:\Users\AMD>dig dnsleaktest.com CHAOS
;; ;; Question section mismatch: got dnsleaktest.com/A/IN

; <<>> DiG 9.17.15 <<>> dnsleaktest.com CHAOS
;; global options: +cmd
;; connection timed out; no servers could be reached

* lightnode-sgn

With CHAOS output

; <<>> DiG 9.17.15 <<>> grc.com CHAOS
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19921
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 7

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;grc.com.                       CH      A

;; ANSWER SECTION:
grc.com.                28800   IN      A       4.79.142.200

;; ADDITIONAL SECTION:
server.nextdns.io.      0       CH      TXT     "lightnode-sgn-1"
profile.nextdns.io.     0       CH      TXT     "fpfcc07fc612f73201"
client.nextdns.io.      0       CH      TXT     "171.233.58.XXX"
proto.nextdns.io.       0       CH      TXT     "DOH"
client-name.nextdns.io. 0       CH      TXT     "nextdns-windows"
smart-ecs.nextdns.io.   0       CH      TXT     "27.72.0.0/24"

;; Query time: 494 msec
;; SERVER: 45.90.28.68#53(45.90.28.68) (UDP)
;; WHEN: Tue Feb 10 12:08:02 SE Asia Standard Time 2026
;; MSG SIZE  rcvd: 323


; <<>> DiG 9.17.15 <<>> dnsleaktest.com CHAOS
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28652
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 7

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;dnsleaktest.com.               CH      A

;; ANSWER SECTION:
dnsleaktest.com.        300     IN      A       23.239.16.110

;; ADDITIONAL SECTION:
profile.nextdns.io.     0       CH      TXT     "fpfcc07fc612f73201"
proto.nextdns.io.       0       CH      TXT     "DOH"
server.nextdns.io.      0       CH      TXT     "lightnode-sgn-1"
client.nextdns.io.      0       CH      TXT     "171.233.58.XXX"
client-name.nextdns.io. 0       CH      TXT     "nextdns-windows"
smart-ecs.nextdns.io.   0       CH      TXT     "27.72.0.0/24"

;; Query time: 625 msec
;; SERVER: 45.90.28.68#53(45.90.28.68) (UDP)
;; WHEN: Tue Feb 10 12:08:15 SE Asia Standard Time 2026
;; MSG SIZE  rcvd: 339

* NextDNS Anycast server

; <<>> DiG 9.17.15 <<>> grc.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19806
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;grc.com.                       IN      A

;; ANSWER SECTION:
grc.com.                28800   IN      A       4.79.142.200

;; Query time: 681 msec
;; SERVER: 45.90.28.0#53(45.90.28.0) (UDP)
;; WHEN: Tue Feb 10 22:41:10 SE Asia Standard Time 2026
;; MSG SIZE  rcvd: 52


; <<>> DiG 9.17.15 <<>> dnsleaktest.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29772
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;dnsleaktest.com.               IN      A

;; ANSWER SECTION:
dnsleaktest.com.        300     IN      A       23.239.16.110

;; Query time: 485 msec
;; SERVER: 45.90.28.0#53(45.90.28.0) (UDP)
;; WHEN: Tue Feb 10 22:41:23 SE Asia Standard Time 2026
;; MSG SIZE  rcvd: 60

* Quad9

; <<>> DiG 9.17.15 <<>> grc.com @9.9.9.11
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34971
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;grc.com.                       IN      A

;; ANSWER SECTION:
grc.com.                28800   IN      A       4.79.142.200

;; Query time: 591 msec
;; SERVER: 9.9.9.11#53(9.9.9.11) (UDP)
;; WHEN: Tue Feb 10 22:46:58 SE Asia Standard Time 2026
;; MSG SIZE  rcvd: 52


; <<>> DiG 9.17.15 <<>> dnsleaktest.com @9.9.9.11
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 37849
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;dnsleaktest.com.               IN      A

;; ANSWER SECTION:
dnsleaktest.com.        300     IN      A       23.239.16.110

;; Query time: 312 msec
;; SERVER: 9.9.9.11#53(9.9.9.11) (UDP)
;; WHEN: Tue Feb 10 22:47:40 SE Asia Standard Time 2026
;; MSG SIZE  rcvd: 60

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2 wk agoLast active
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Some domain names with ultralow servers (with IPv6) are not being resolved

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