topic Re: Reverse ptr record in Tech Help - Software/Hardware etc

Reverse ptr record

lazyd0g — Wed, 20 Feb 2019 16:36:45 GMT

Hi all.

Currently hosting my own mail server handling email for gooduse.co.uk.

Everything else is setup correctly.

Got flagged on Spamhaus PBL list.

SMTP Banner Check Reverse DNS does not match SMTP Banner More Info
SMTP Reverse DNS Mismatch OK - 80.229.248.90 resolves to lazyd0g.plus.com
SMTP Valid Hostname OK - Reverse DNS is a valid Hostname
SMTP TLS OK - Supports TLS.
SMTP Connection Time 1.031 seconds - Good on Connection time
SMTP Open Relay OK - Not an open relay.
SMTP Transaction Time 3.391 seconds - Good on Transaction Time

https://mxtoolbox.com/SuperTool.aspx?action=mx%3agooduse.co.uk&run=toolpage#

Pref Hostname IP Address TTL
10 lazyd0g.plus.com 80.229.248.90 24hrs
DMARC Record Published DMARC Record found
DMARC Policy Not Enabled DMARC Quarantine/Reject policy enabled
DNS Record Published DNS Record found

I requested a reverse ptr record via the "Help Assistant" and got this reply.

I'm afraid that we are unable to edit the domain record on lazyd0g.plus.com. This domain points to the Plusnet provided webspace and we do not offer any changes to this with regards to our support level.

Is this correct? www.lazyd0g.plus.com *does* resolve to plusnet webspace however, http://lazyd0g.plus.com does not.

Should I have asked for something different?

ta for your input.

Steve

Re: Reverse ptr record

Jon — Wed, 20 Feb 2019 17:01:29 GMT

Hi @lazyd0g

We can't alter the .plus.com rDNS, but we can add a custom one based on your domain name.

If you can create a forward record i.e. something.yourdomain.co.uk, then we can set up the reverse for you from this end so that something.yourdomain.co.uk looks up to your own IP address.

Therefore, if you can create the forward record and let us know what it is via the ticket on your account, we can get this set up from this end for you.

Thanks

Re: Reverse ptr record

lazyd0g — Wed, 20 Feb 2019 17:04:16 GMT

OK. forget my question! Solved it. \0/

Managed to change my smtp banner to lazyd0g.plus.com

Seems to have resolved the issue.

Re: Reverse ptr record

bobpullen — Wed, 20 Feb 2019 17:24:49 GMT

@lazyd0g, the reply you received via the Help assistant was misinformed.

The crux of the issue is this:

SMTP Reverse DNS Mismatch OK - 80.229.248.90 resolves to lazyd0g.plus.com

Which is related to the reverse DNS record for your IP address.

We can change this for you despite what you were told. Normally we would ask you to prove ownership of the domain by creating a forward A record pointing to your Plusnet IP address, but that's not necessary in your case as you already have an MX record pointing to lazyd0g.plus.com:

C:\Users\604573344>nslookup -type=mx gooduse.co.uk
Server:  UnKnown
Address:  212.159.8.120

Non-authoritative answer:
gooduse.co.uk   MX preference = 10, mail exchanger = lazyd0g.plus.com

If you decide you want to change your SMTP banner back to gooduse.co.uk, then I'll happily change the reverse DNS of your IP to match.

PS. Doesn't make much difference in the grander scheme of things, but it's arguably more professional to configure the MX records for gooduse.co.uk like this:

gooduse.co.uk.      MX       mail.gooduse.co.uk.
mail                A        80.229.248.90

Re: Reverse ptr record

lazyd0g — Wed, 20 Feb 2019 19:22:15 GMT

Hi Bob,
yes please! It's always nice to have things properly complete! 🙂

Thank you.

Steve

Re: Reverse ptr record

bobpullen — Thu, 21 Feb 2019 08:34:19 GMT

@bobpullen wrote:

Normally we would ask you to prove ownership of the domain by creating a forward A record pointing to your Plusnet IP address...

@lazyd0g, looks like you're going to have to do this. There's now a validation check in place at our side that makes sure the forward record matches the reverse when trying to change an rDNS record.

Couple of options:-

1. You create an A record with the domain host to point gooduse.co.uk to 80.229.248.90. This assumes of course that gooduse.co.uk is not being used for anything else (email accepted). We then change rDNS for the IP and you update your smtp banner to gooduse.co.uk

2. If gooduse.co.uk is being used for something else, then you could configure your MX records like I suggested previously and we could change the rDNS for the IP to mail.gooduse.co.uk instead. You then update your smtp banner to mail.gooduse.co.uk

Re: Reverse ptr record

lazyd0g — Thu, 21 Feb 2019 10:38:33 GMT

Hi again @bobpullen

seems a bit hoop-jumpy given I obviously have control of gooduse.co.uk.

Anyways, A record created:

host -a gooduse.co.uk
Trying "gooduse.co.uk"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55141
;; flags: qr rd ra; QUERY: 1, ANSWER: 11, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;gooduse.co.uk. IN ANY

;; ANSWER SECTION:
gooduse.co.uk. 86400 IN TXT "google-site-verification=uRICq8iwkmw_VrNY2KF65PMbktMaTRQxkCova7JNuj0"
gooduse.co.uk. 86400 IN TXT "v=spf1 mx a:lazyd0g.plus.com include:spf.ukservers.net ~all"
gooduse.co.uk. 86400 IN SOA ns0.phase8.net. support.phase8.net. 2019022101 28800 3600 604800 86400
gooduse.co.uk. 86400 IN MX 10 lazyd0g.plus.com.
gooduse.co.uk. 86215 IN A 35.172.94.1
gooduse.co.uk. 86215 IN A 80.229.248.90
gooduse.co.uk. 86215 IN A 85.233.160.147
gooduse.co.uk. 86215 IN A 100.24.208.97
gooduse.co.uk. 86400 IN NS ns0.phase8.net.
gooduse.co.uk. 86400 IN NS ns1.phase8.net.
gooduse.co.uk. 86400 IN NS ns2.phase8.net.

ta.

Steve

Re: Reverse ptr record

bobpullen — Sat, 23 Feb 2019 16:15:02 GMT

@lazyd0g, thanks. It'll need to wait until I'm back in the office on Monday. Give me a nudge in the afternoon if I've not responded by then.

Re: Reverse ptr record

lazyd0g — Thu, 28 Feb 2019 16:26:09 GMT

Hi @bobpullen

this is a nudge.......

nudge, nudge!

Re: Reverse ptr record

bobpullen — Thu, 28 Feb 2019 16:58:34 GMT

Grrr, still giving me the same error:

"We cannot change the rDNS if the record doesn't resolve to the IP. Get the customer to change this and try again."

Are you able to remove the other A records? I'd imagine that will do the trick.

gooduse.co.uk.          86343   IN      A       35.172.94.1
gooduse.co.uk.          86343   IN      A       100.24.208.97
gooduse.co.uk.          86343   IN      A       85.233.160.147

Alternative is for me to enquire about one of our Ops engineers making a manual change. That's likely to be a fairly laborious process though (if it's even possible).

Re: Reverse ptr record

lazyd0g — Thu, 28 Feb 2019 17:06:29 GMT

Hi again @bobpullen

might take a bit longer update at your end of the internet.......

host -a gooduse.co.uk
Trying "gooduse.co.uk"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 39745
;; flags: qr rd ra; QUERY: 1, ANSWER: 8, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;gooduse.co.uk.           IN   ANY

;; ANSWER SECTION:
gooduse.co.uk.       86350   IN   TXT   "v=spf1 mx a:lazyd0g.plus.com include:spf.ukservers.net ~all"
gooduse.co.uk.       86350   IN   TXT   "google-site-verification=uRICq8iwkmw_VrNY2KF65PMbktMaTRQxkCova7JNuj0"
gooduse.co.uk.       86350   IN   MX   10 lazyd0g.plus.com.
gooduse.co.uk.       86350   IN   SOA   ns0.phase8.net. support.phase8.net. 2019022801 28800 3600 604800 86400
gooduse.co.uk.       86350   IN   A   80.229.248.90
gooduse.co.uk.       86350   IN   NS   ns1.phase8.net.
gooduse.co.uk.       86350   IN   NS   ns2.phase8.net.
gooduse.co.uk.       86350   IN   NS   ns0.phase8.net.

Received 340 bytes from 127.0.0.53#53 in 2 ms

Re: Reverse ptr record

bobpullen — Fri, 01 Mar 2019 10:51:41 GMT

@lazyd0g, got there in the end

"Your reverse DNS has now been updated and the changes should take effect within 24 hours."

Let me know if you still can't see any change come tomorrow.

Re: Reverse ptr record

lazyd0g — Fri, 01 Mar 2019 10:58:56 GMT

Hi @bobpullen

Thank you.

Re: Reverse ptr record

spgrnic — Fri, 24 May 2019 11:11:51 GMT

I have the same issue as detailed in this community post https://community.plus.net/t5/Tech-Help-Software-Hardware-etc/Reverse-ptr-record/td-p/1615136

I have a fixed IP Address 212.159.45.30 and am running a mail server with 3 domains on it. The DNS for these domains I manage myself through https://www.123-reg.co.uk/

So I would like:

webmail.hermes-it.co.uk for a reverse DNS lookup to resolve to 212.159.45.30
webmail.ecalpemos.co.uk for a reverse DNS lookup to resolve to 212.159.45.30
webmail.phaedra.me.uk for a reverse DNS lookup to resolve to 212.159.45.30

If I can only have one domain resolving to 212.159.45.30 then it should be webmail.hermes-it.co.uk

If you need to speak to me about this, please phone me on either 01252 626 878 or 07833 621 612

Thanks

Trisha

Re: Reverse ptr record

Teece — Wed, 17 Feb 2021 15:50:28 GMT

Old news, but in case anyone is looking at this - what spgrnic is asking for isn't possible. Reverse DNS works on the IP address, and returns the PTR entry, which is the 'text' value. So it's only possible to map an IP address to a single domain name. You'd need separate IP addresses to support each domain.

Re: Reverse ptr record

JoeJohnJames — Mon, 14 Jun 2021 10:33:59 GMT

Presumably one approach to this is to use only one of these domains for the mail server for all of them, such as mail.ecalpemos.co.uk, and then set the MX records for each of the domains to point at this mail server. You can then have the rDNS for your public IP address to point to that mail server's domain and it should all work fine.

Alternatively you could get a new domain that you only use for your mail server such as mydomain.com and point the MX record for all of them at mail.mydomain.com, with the rDNS for your public IP address pointing at mydomain.com.

Obviously there are some shortcomings of hosting your own resources from a domestic-style internet connection where you only have one static IP address, but this should be a way around running mail servers for multiple domains when that is the case.

I assume that this approach would also work if you had multiple public IP addresses as they could all be set for rDNS for the IP to point to this single domain.

Re: Reverse ptr record

mbcookma — Sat, 19 Feb 2022 16:14:22 GMT

flip! no wonder these forms are so aged: I just spent time clicking pictures of traffic lights and boats to get this logged in!

Thanks for the post mentioning PTR , really got me started.

For other dedicated trawlers I found this a helpful site: https://support.dnsmadeeasy.com/support/solutions/articles/47001001439-pointer-ptr-record

Re: Reverse ptr record

Sulphurik — Sun, 04 Sep 2022 08:54:49 GMT

Hi,

Sorry to necro this thread, I'm trying to setup an email server and I believe outgoing messages from the server are being blocked because my PTR isn't correct. Are you able to assist?

Re: Reverse ptr record

Teece — Sun, 04 Sep 2022 12:09:42 GMT

It's unlikely that this is the main cause of messages being blocked. How are you routing your messages? Most major e-mail hosts (Google etc) will block private servers - you should be using the Plusnet smarthost to send your outgoing mail.

Re: Reverse ptr record

Sulphurik — Sun, 04 Sep 2022 17:18:42 GMT

It turns out that the cause was missing DMARC and incorrectly formatted SPF records. After fixing those records test emails have arrived at Gmail, Yahoo and Outlook.

Although relaying is a perfectly suitable solution it does add some latency to the delivery process so I'm glad it's working now, I didn't actually know about the relay servers tbh.