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I am trying to setup BIND9 (Master and Slave DNS Servers), which I have done, and it is working as it should be (I believe). I can dig the domain name I am using and IPs and extract all the neccessary details from the zone file.

DNS1 is running on abc.abc.abc.abc IP Address DNS2 is running on bcd.bcd.bcd.bcd IP Address

The mail Server will be running on cde.cde.cde.cde IP addressed Server.

However, when I do a dnsstuff.com check, it warns about the reverse IP not matching. The PTR bit works fine, it reports the listed IP for the PTR Record in my in-addr.arpa file.

But no matter what I do in setting the A Record in the domain name zone file and the MX record, it only reports the IPs of the DNS Servers, abc and bcd.

$TTL    360
@       IN      SOA     dns1.example.com. admin.example.com. (
                        2020011912      ; Serial
                        604800          ; Refresh
                        86400           ; Retry
                        2419200         ; Expire
                        604800 )        ; Negative Cache TTL

; Name Servers - NS Records

@               3600    IN      NS      dns1.example.com.
@               3600    IN      NS      dns2.example.com.

; Name Servers - A Records

dns1            3600    IN      A       abc.abc.abc.abc
dns2            3600    IN      A       bcd.bcd.bcd.bcd

; A Records

www             3600    IN      A       cde.cde.cde.cde
@               360     IN      A       cde.cde.cde.cde
ct1             360     IN      A       cde.cde.cde.cde
mail            360     IN      A       cde.cde.cde.cde

; MX Records

example.com.       3600    MX 0    mail.example.com.

This is the error I get.

One or more addresses referenced by MX records do not have a matching reverse DNS entry. This can cause problems for mail deliverability for these servers. Some mail platforms will not accept or will delay email coming from mismatched addresses. The addresses without matching reverse DNS entries are:

abc.abc.abc.abc has mail.example.com. | cde.cde.cde.cde listed.
bcd.bcd.bcd.bcd has mail.example.com. | cde.cde.cde.cde listed.

I purchased my own Domain Name and registered the name servers on the website and assigned the IPs to my name servers, and I can ping, dig and nslookup etc, relevant details from Ubuntu.

I am just at a loss as to why, it keeps listing the wrong IP.

I probably have something wrong in a different configuration file.

Many Thanks.

Laird Brian Clough
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  • What does "The PTR bit works fine, it reports the listed IP for the PTR Record in my in-addr.arpa file." mean? For some spam filtering to work DNS does a lookup of the MX record, gets the IP address and then it does a reverse lookup. (Which uses the in-arpa" bit) The reverse DNS needs to match the MX record. Here's what may be the thing though. Your IP address provider needs to delegate the appropriate in-arpa subdomain to your name server or it won't be used for reverse lookup. – davidgo Jan 19 '20 at 17:25
  • Well, if I "dig -x my ip address" - It returns in the answers "the correct IP.in-addr.arpa. 360 IN PTR mail.example.com. And I did suspect it was going to require a further phone call to my ISP. – Laird Brian Clough Jan 19 '20 at 17:30
  • Have you tried dig @1.1.1.1 -x IP.add.re.as ? (I'm wondering if dig is looking at your DNS which knows what it thinks, rather then what the rest of the internet sees?) – davidgo Jan 19 '20 at 18:23
  • ;MY IP BACKWARDS.in-addr.arpa. IN PTR ;; AUTHORITY SECTION: xxx.xx.in-addr.arpa. 148662 IN SOA midir.vodafone.ie. administrator.vodafone.ie. 48717102 86400 7200 3600000 172800 – Laird Brian Clough Jan 19 '20 at 19:52
  • Ah yes, so I am resolving internally, not externally. *nods* Right, ISP it is tomorrow morning. Thank you for your help. :-) – Laird Brian Clough Jan 19 '20 at 19:53

0 Answers0