SOLVED The system failed to complete validation of “my_domain.com”’s “PTR” because of an error: (.......in-addr.arpa/PTR) timeout

Operating System & Version
Centos 7.9
cPanel & WHM Version
V90.0.17

bitpt

Active Member
Sep 28, 2006
25
2
153
An error appears randomly when testing "email deliverability"

"The system failed to complete validation of" srv.example.com "" PTR "because of an error: (....... in-addr.arpa/PTR) timeout.

After some tests (2 or 3) blue "properly configured" appears.

Testing in all dns tools that I know and other searched in GG, none of them gives an error in the PTR.
Performing the tests requested by the hosting provider.

#speedtest-cli
Testing download speed
Download: 922.93 Mbit/s
Testing upload speed
Upload: 928.80 Mbit/s

ehttool eth0
Settings for eth0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Advertised pause frame use: Symmetric
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Link partner advertised pause frame use: No
Link partner advertised auto-negotiation: Yes
Link partner advertised FEC modes: Not reported
Speed: 1000Mb/s

# iperf3
ID] Interval Transfer Bandwidth Retr Cwnd
[ 4] 0.00-1.00 sec 114 MBytes 954 Mbits/sec 0 363 KBytes
[ 4] 1.00-2.00 sec 113 MBytes 945 Mbits/sec 0 368 KBytes
[ 4] 2.00-3.00 sec 112 MBytes 938 Mbits/sec 0 369 KBytes
[ 4] 3.00-4.00 sec 113 MBytes 945 Mbits/sec 0 369 KBytes
[ 4] 4.00-5.00 sec 112 MBytes 938 Mbits/sec 0 369 KBytes
[ 4] 5.00-6.00 sec 112 MBytes 940 Mbits/sec 0 372 KBytes
[ 4] 6.00-7.00 sec 112 MBytes 940 Mbits/sec 0 389 KBytes
[ 4] 7.00-8.00 sec 112 MBytes 939 Mbits/sec 0 411 KBytes
[ 4] 8.00-9.00 sec 112 MBytes 942 Mbits/sec 0 411 KBytes
[ 4] 9.00-10.00 sec 113 MBytes 946 Mbits/sec 0 411 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-10.00 sec 1.10 GBytes 943 Mbits/sec 0 sender
[ 4] 0.00-10.00 sec 1.10 GBytes 941 Mbits/sec receiver

# mtr -rw -c 100 ... OUT and IN

no significant packet loss

Can be a Cpanel whm Issue??
 

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Last edited:

cPRex

Jurassic Moderator
Staff member
Oct 19, 2014
2,298
306
213
cPanel Access Level
Root Administrator
Hey there! Sorry to hear about that issue.

When this happens, are you able to perform a "dig -x 1.2.3.4" command from the server, where the "1.2.3.4" is your server's IP address that you're checking? That's all that happens with the rDNS check, so it would be interesting to know if that also is not working during the times you experience those issues. If that does fail during those times, but works during other times, that would point to some type of intermittent network issue on the machine.
 

bitpt

Active Member
Sep 28, 2006
25
2
153
Hey there! Sorry to hear about that issue.

When this happens, are you able to perform a "dig -x 1.2.3.4" command from the server, where the "1.2.3.4" is your server's IP address that you're checking? That's all that happens with the rDNS check, so it would be interesting to know if that also is not working during the times you experience those issues. If that does fail during those times, but works during other times, that would point to some type of intermittent network issue on the machine.
I put all network tests, no failures, and i saw same issue reported from other users in forum in last months.
Dig or all other test are ok...
I "guess" this is a cpanel problem all tests are ok from outside/inside and from all resolvers.
Be my guest if you want investigate, no email failures reported from users accounts, only errors in whm or cpanel when email deliverability is tested

Seems a false positive, but some users(clients) report this error whitout failures in emails.
Disable firewalls makes no difference.
 
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