Reverse DNS Issue


T

Tony Crouch

I am running DNS/IIS/Email on my Win2K server. It is
strictly a public server for web/email services. I am
subnetted off of my ISP's domain, and my IP address is
68.156.76.92 & .93. I setup all my forward DNS entries
and my reverse DNS entry of 76.156.68.in-addr.arpa

The problem I have is that whenever you try to reverse
lookup on either of my IP's (or any of my hostnames), it
says that my ISP's DNS server is the authorative for the
subnet and there are no PTR records. How can I get
reverse lookup for my domains and IP's to go to my server
to get PTR records instead of to my ISP's DNS servers?

Thanks!
 
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H

Herb Martin

The problem I have is that whenever you try to reverse
lookup on either of my IP's (or any of my hostnames), it
says that my ISP's DNS server is the authorative for the
subnet and there are no PTR records.
Of course it does because they are authoritative for those
ranges. Generally the ISP OWNS the IP addresses and
you must get the ISP to setup reverse lookups if you NEED
them.
How can I get
reverse lookup for my domains and IP's to go to my server
to get PTR records instead of to my ISP's DNS servers?
Only by getting the ISP to do it or to "Delegate" to you but for
2 addresses they are NOT going to delegate (I bet.)

Just ask your ISP to add the two records to the reverse lookup
zones -- or use NSLookup or Dig to find out if they already have
done this: Many ISPs just build generic reverses for all their
customer IPs, e.g., addr1.customer7.com 192.168.128.1 etc.

Then if you need to ID your email server or something just use
THAT name which the OTHER email server (etc) can reverse to
"prove" ('satisfy' is closer)to itself that you are who you claim.

Your reverse name doesn' t have any NECESSARY relationship
to your Email Domains -- I have 20 email domains on my SMTP
server but it can only reverse to ONE name.
 
T

Tony Crouch

Thanks for the advice. I was worried because someone said
that alot of mail servers are starting to require reverse
lookup before accepting mail. Does that make sense?
 
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H

Herb Martin

Thanks for the advice. I was worried because someone said
that alot of mail servers are starting to require reverse
lookup before accepting mail. Does that make sense?
Sure, it makes perfect sense -- if your email server claims to be
"x.y.com" then they want to know you are SENDING from the
ADDRESS assigned to "x.y.com". It's not perfect but it does
prove that the "owner" of the IP address range "knows who you
are."

So, when you fill in the SMTP field for "email server name" match
it to the reverse name (that you gave the ISP or that they gave you.)

Note: I can send and receive mail for all of my email "domains" even
though the same PHYSICAL, NAME, and IP, server does all the
sending.
 

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