SMTP Valid Hostname > Reverse DNS is not a valid Hostname More Info
SMTP Reverse DNS Mismatch > OK - 121.200.50.7 resolves to mail.xxxx.com
SMTP Banner Check > OK - Reverse DNS matches SMTP Banner
SMTP TLS > OK - Supports TLS.
SMTP Connection Time > 1.172 seconds - Good on Connection time
SMTP Open Relay > OK - Not an open relay.
SMTP Transaction Time > 4.063 seconds - Good on Transaction Time

Hi Everybody,

This is my First Post Pls help

What is exactly means Reverse DNS is not valid host. I have my own IP and have our Own DNS server, to provide reverse lookup, For one my clients, when check MX tools for rdns check it showing Reverse DNS is not valid Host,I have configured everything fine .even I dig for rdns it gives exact answers. Then what it is. How would I resolve this and how will I improve Dns Responding time

My DNS Configured in Cent OS, I have too many zones all it Authoritative DNS for our own Pool of IP. It has external view and Internal view configured.

For this post whether I need to configure Host or what .

So please give me suggestion


Thanks

Murganandan
Coimbatore

Reverse DNS is IP address mapping of a domain.basically this has to be informed to your internet IP provider to point the IP to your domain.

We are the ISP provider, we have our Own Pools of IP, providing reverse DNS to our customers. When I test with MX tool box to test rdns it gives the Error
SMTP Valid Hostname Reverse DNS is not a valid Host name, I searched google to get exact view, but I could not get. What should I do to to avoid SMTP valid Hostname.Do I need to configure anything to point SMTP.Please clarify.
Herewith I have given My zone file configuration

$TTL 86400
@ IN SOA wls. root.wls. (
2012100102 ; Serial
28800 ; Refresh
14400 ; Retry
3600000 ; Expire
86400 ) ; Minimum

50.200.121.in-addr.arpa. IN NS dns1.wls.net.in.

2 IN PTR mail.makcontrols.com.
2 IN PTR mail.gpslocker.com.
2 IN PTR mail.airmak.com.
2 IN PTR smtp.airmak.com.
2 IN PTR airmak.com.
2 IN PTR mail.manuneethi.net.
2 IN PTR mail.makindialimited.com.
3 IN PTR mail.makcontrols.com.
3 IN PTR mail.gpslocker.com.
3 IN PTR mail.airmak.com.
3 IN PTR smtp.airmak.com.
3 IN PTR airmak.com.
3 IN PTR mail.manuneethi.net.
3 IN PTR mail.makindialimited.com.
4 IN PTR mail.makcontrols.com.
4 IN PTR mail.gpslocker.com.
4 IN PTR mail.airmak.com.
4 IN PTR smtp.airmak.com.
4 IN PTR airmak.com.
4 IN PTR mail.manuneethi.net.
4 IN PTR mail.makindialimited.com.
5 IN PTR mail.makcontrols.com.
5 IN PTR mail.gpslocker.com.
5 IN PTR mail.airmak.com.
5 IN PTR smtp.airmak.com.
5 IN PTR airmak.com.
5 IN PTR mail.manuneethi.net.
5 IN PTR mail.makindialimited.com.
6 IN PTR mail.makcontrols.com.
6 IN PTR mail.gpslocker.com.
6 IN PTR mail.airmak.com.
6 IN PTR smtp.airmak.com.
6 IN PTR airmak.com.
6 IN PTR mail.manuneethi.net.
6 IN PTR mail.makindialimited.com.
7 IN PTR mail.makcontrols.com.
7 IN PTR mail.gpslocker.com.
7 IN PTR mail.airmak.com.
7 IN PTR smtp.airmak.com.

Please give suggestion


Muruganandan
Coimbatore

Can you tell me is it for a specific domain or for all of the domains? Can you give me the result / output for the domain mail.makcontrols.com?

This is only for the Domain mail.makcontrols.com. We have another one domain configured in the same Network It gives everything perfect output when I test with mxtoolbox for reverse,smtp lookup.please find the below out of MXTOOLBOX Output for the domain,,





For other Domain

SMTP Reverse DNS Mismatch OK - 121.200.55.19 resolves to zimbramail.asecin.co.in
SMTP Valid Hostname OK - Reverse DNS is a valid Hostname
SMTP Banner Check OK - Reverse DNS matches SMTP Banner
SMTP TLS OK - Supports TLS.
SMTP Connection Time 1.156 seconds - Good on Connection time
SMTP Open Relay OK - Not an open relay.
SMTP Transaction Time 4.078 seconds - Good on Transaction Time

For the Subjected Domain mail.makcomtrols.com

SMTP Valid Hostname Reverse DNS is not a valid Hostname More Info
SMTP Transaction Time 19.896 seconds - Not good! on Transaction Time More Info
SMTP Reverse DNS Mismatch OK - 121.200.50.7 resolves to mail.makcontrols.com
SMTP Banner Check OK - Reverse DNS matches SMTP Banner
SMTP TLS OK - Supports TLS.
SMTP Connection Time 2.907 seconds - Good on Connection time
SMTP Open Relay OK - Not an open relay.


Thanks and Regards

Muruganandan
Coimbatore

After analyzing, the reason for "not a valid hostname" is multiple ptr records for a single IP. For eg if you ping -a the IP from a Windows system it gets resolved to different hostname. Basically multiple ptr for a single IP has a downside when it comes at SMTP level. I could say it is an improper configuration at the DNS level.

In your case, if nothing is possible , then you set one single ptr eg. smtp.isp.mail and define the hostname in the spf record to be at the acceptance side when sending an email.

Hope I have been of assistance.