[CLUE-Tech] reverse DNS

[Angelo Bertolli]

Even if there is no RDNS, can't you still block based on IP address?  I 
mean is it now a requirement to have RDNS set up?

Adam Bultman wrote:

> Well, it doesn't really 'keep it in check' unless you are specifically 
> denying the ability of people without RDNS to send you mail, like AOL 
> does.
>
> RDNS is *meant* to assist with things like mail, etc so that you can 
> trully 'know' where mail is coming from. Unfortunately, very few 
> people actually deny mail based on RDNS info because you'll be 
> blocking too many people.
>
> For mail, SPF is the next big thing...
>
> Adam
>
> William wrote:
>
>> Simply put, it serves something like an ID card for your host.  
>> Additionally, thanks to the
>> delegated nature of DNS and who controls the DNS servers, it is much 
>> more difficult to spoof than,
>> say, an SMTP HELO response.  I can't say how many thousands of hits I 
>> get against my servers ever
>> day that 'claim' to be one host, when their RDNS lookup indicates who 
>> they truly are -- usually
>> dial-up, cable, and DSL users, all from dynamic IP beds.  Spoofing is 
>> rampant, and RDNS help to
>> keep it in check.
>>
>>