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Questions tagged [reverse-dns]

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Reverse DNS lookup is the determination of a domain name that is associated with a given IP address using the Domain Name System (DNS) of the Internet.

584 questions
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Score of 0
1 answer
94 views

We have an AD-integrated DNS environment with ~80 reverse lookup zones built up over years, all created independently with no parent zone. The 10.in-addr.arpa parent does not exist; we just have ...
Score of 6
1 answer
587 views

I'm debugging a very strange issue on a Proxmox server (running on Debian 12). It is connected via a 10G link (SFP+ DAC) to a switch. Another 10G link goes to another very similar server: SrvA -- 10G ...
Score of 3
1 answer
826 views

I’m sending email from my mail server to Gmail. Gmail rejects the message with the following error: 550 5.7.25 The IP address sending this message does not have a PTR record setup or the ...
Score of 4
0 answers
425 views

I'm running Postfix 3.10 on an Ubuntu 24.04 server, with these settings in /etc/postfix/main.cf: smtpd_client_restrictions = # previous entries omitted for brevity warn_if_reject ...
Score of 1
1 answer
132 views

I am investigating reverse DNS (PTR) records and how they are used today. For example stackoverflow.com resolves to 104.18.32.7 and that IP has zero PTR records (neither does the domain's other IP). ...
Score of 0
1 answer
295 views

On an Ubuntu 24.04 google compute engine VM, Apache 2.4, the following warning is in the apache logs: [ssl:warn] a.b.c.d.bc.googleusercontent.com:443:0 server certificate does NOT include an ID which ...
Score of 0
0 answers
196 views

I am experiencing an ERR_CONNECTION_TIMED_OUT when trying to access my GCE VM from the public internet on port 80. I have run an exhaustive series of checks and can confirm the following: Application ...
Score of 0
1 answer
134 views

I have this bind9 settings: named.conf: include "/etc/bind/named.conf.options"; include "/etc/bind/named.conf.local"; named.conf.options: include "/etc/bind/rndc.key"; ...
Score of -1
1 answer
204 views

We are debugging the logging of some services, such as the moving_data_to_hdfs.service, on our RHEL 7.6 machines. We ran the following command: journalctl -u moving_data_to_hdfs.service >/log.txt ...
Score of -1
1 answer
246 views

i have an issue with my PTR Record. I've configured my DNS PTR settings, but MXToolbox doesn't recognize them. What's wrong? MXSuptertoolbox DNS Settings All other DNS settings work
Score of 0
1 answer
209 views

If you have a minute, I am a little confused about addressing rDNS warning for outbound emails. I have this setup... http web server (ip 1.2.3.4, hostname apps.acme.com) smtp mail server (ip 1.2.3.5, ...
Score of 0
1 answer
213 views

I am monitoring a Paragon Insights server (Healthbot), Ubuntu system with kubernets environment, one of the containers called Alert has installed in this the Exim4 tool as MTA to send email ...
Score of 0
1 answer
709 views

I've set up PTR record on the DNS server of our organisation. Reverse lookup works on our network, but from a different network, it does not work. It seems to me that something needs to be done on the ...
Score of 2
3 answers
1612 views

I'm searching for domains that own IP addresses that I'm seeing traffic to in my GCP network, in order to configure a firewall rule for that specific domain. For 142.251.211.234, I know it's a Google ...
Score of 0
1 answer
493 views

I'm setting up reverse DNS for IPv6 using PowerDNS and could use some assistance with a configuration issue. I successfully created the reverse DNS zone and added a PTR record, but the record is not ...

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