PTR delegation

Jeremy C. Reed jreed at
Wed Jun 3 19:02:50 UTC 2009

On Wed, 3 Jun 2009, Scott Haneda wrote:

> Hoping I can get a walk through in simple terms, but also a pointer to 
> some docs where I can dive into the details.  I think I am finding what 
> I want in the docs, but those docs come up 404 since the isc site 
> changed things a bit, from there, I generally can not locate the old doc 
> file.

What documents? I will help make sure they are visible or fix links if 

> 1) Is it possible to determine what ip range/space has been given to 
> user of that IP space?  For example, in a colocation environment, I am 
> given say, a /24, and I want to look that up and see if it really is a 
> /24.  I have found the -x option which is making life a lot easier to 
> find PTR records.

Someone else can answer that.

> 2) Given an IP that does not have a PTR, how do I determine if it has 
> been "sub delegated" (?) to the user of that IP?  I need to learn 
> whether or not I need to contact the IP provider, and ask for a PTR 
> record, or if I need to add one in myself.

Use dig to follow the delegation. For example:

     dig -x

     dig -x

(look at authority section)

     dig -x

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