OVH IPv6 Reverse DNS not working despite IPv6 pinging

Help with Setup/Upgrade
1

I setup MIAB on a new OVH server (I’m going to use outbound relay to get around OVH’s bad IP reputation.)

Brand new Ubuntu 22.04 install. IPv4 and IPv6 configured and pinging. I successfully was able to setup Reverse DNS for the IPv4 no problem.

However, if I try to configure box.mydomain.com for IPv6 Reverse DNS in OVH’s panel, I get the following error:

An error has occurred updating the reverse path. Cannot check if box.mydomain.com. resolves to 2604:2dc0:0101:0200:0000:0000:0000:xxxx

Which is simply not true. If I perform a ping6 box.mydomain.com I see the ping results coming back with my VPS’ IPv6 address.

OVH seems to be a little wonky, but their Epyc servers are cheap and fast! I’d really like to get this working.

2

I had the same thing some while ago, it sometimes takes a while while for a change in DNS to be known everywhere. Also, are you pinging from e.g. your home computer, or from the box itself?

3

You could also check status of your rDNS/PTR record with DIG command:

sudo apt -y install dnsutils

dig -x 2604:2dc0:0101:0200:0000:0000:0000:xxxx
or
dig -x 234.1.1.1

4

Thank you, but that’s not it. When I ping the IPv6 version of the website from across the globe it is responding with my the IPv6 address of my VPS.

5

Thank you. Yes, I did this. The dig command responds, but it’s with the generic hostname of my OVH VPS server. This is what’s really strange, because the hostname has been updated to box.mydomain.com and IPv4 reverse DNS worked just fine.

I can ping box.mydomain.com and it works fine. I can run dig -x xx.xxx.xx.xx (IPf4 address) and it comes back with my reverse DNS record.

Something weird is going on with IPv6 where it’s not seeing the box.mydomain.com host name…

6

Try this for IPv4:
ping4 box.mydomain.com
and this for IPv6
ping6 box.mydomain.com

7

The answer from DIG should be:

;; ANSWER SECTION:
xxx.xxx.xxx.xxx.in-addr.arpa. 3467 IN PTR box.mydomain.com.

and for IPv6

;; ANSWER SECTION:
x.x.x.x.0.0.0.0.0.0.0.0.0.0.0.0.2.0.1.0.1.0.0.c.d.2.0.2.4.0.6.2.ip6.arpa. 3600 IN PTR box.mydomain.com.

if it is not, then rDNS/PTR record is not set correctly or not propagated yet fully …

8

Yes, that is the problem :laughing: dig -x ipv6 address does NOT return box.mydomain.com because I CAN’T set box.mydomain.com in OVH for the IPv6 address. I get the error:

An error has occurred updating the reverse path. Cannot check if box.mydomain.com. resolves to 2604:2dc0:0101:0200:0000:0000:0000:xxxx

Even though I used this OVH guide to update the hostname of my VPS, my VPS is not seeing this hostname for the IPv6 address.

I use websites like this to ping the IPv6 address of box.mydomain.com and all of the websites ping successfully and show my IPv6 address.

9

Yes, both commands work locally on my MacBook. Both results come back with the correct IPv4 and IPv6 address for box.mydomain.com.

10

I see … OVH and AMZ are quite annoying to run MIAB :frowning:

From memory I know that propagation in OVH has taken forever …
when did you set/requested the rDNS/PTR record to be created with OVH?

11

Yesterday afternoon. It’s now 8:40am here, March 14th.

IPv4 reverse DNS worked almost instantly yesterday after updating the hostname. IPv6… nothing. I tried again this morning and I still get the same error message. IPv6 is pinging across the globe for box.mydomain.com. I see the correct IPv6 address in all ping results. I’ts so frustrating why IPv6 rDNS won’t configure.

12

You could always raise ticket with OVH now … that will take few days for them to answer …