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Old 01-05-2006, 08:01 AM   #1
shadowsa
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dns+dynamicIP+PTR


my ip address is assigned by my isp, and i would like to know if it is possible to set a PTR record for it?
or if this is only possible with cooperation with my isp?
thanks in advance.
 
Old 01-05-2006, 02:00 PM   #2
Darin
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A PTR (Pointer) is a DNS record for the IP subnet (z.y.x.w.in-addr.arpa.), independant of the DNS record(s) for any given domain name. This means it's controlled by the ISP that owns the IP addresses, not by whoever owns any domain names on those IP addresses. Unfortunatly, that means you can't get a reverse lookup record without having your ISP do it. It's also not likely they would set up a reverse lookup record for a dynamic IP address, which isn't the greatest idea anyhow. Which means you probably have to buy a static IP that would probably include the option to add a reverse-lookup PTR record in the deal.
 
Old 01-06-2006, 09:24 AM   #3
shadowsa
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so in other words the service of, for example dyndns, wich offers a subdomain, doesnt work with dunamic ip's???
at least not fully
 
Old 01-06-2006, 11:48 AM   #4
Darin
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It's not an issue of getting a domain name pointed to your IP (dynamic or static) it's one of getting that IP address to also point back to your domain name. Even users of dynamic IP services don't have PTR records for reverse lookup of domain name by IP.

On your Linux box do a dig of some site that offers secure web services, since these sites require reverse lookups for their SSL certificates:

Code:
darin@linux:~$ dig amazon.com
...
;; QUESTION SECTION:
;amazon.com.         IN      A

;; ANSWER SECTION:
amazon.com.     60     IN     A      207.171.175.29
amazon.com.     60     IN     A      72.21.206.5
amazon.com.     60     IN     A      207.171.166.102
...
darin@linux:~$ dig -x 207.171.175.29
...
;; QUESTION SECTION:
;29.175.171.207.in-addr.arpa.   IN      PTR

;; ANSWER SECTION:
29.175.171.207.in-addr.arpa. 7200 IN    PTR     175-29.amazon.com.
...
Now let's take a look at a dynamic site...
Code:
darin@linux:~$ dig kollins.homelinux.com
...
;; QUESTION SECTION:
;kollins.homelinux.com.         IN    A

;; ANSWER SECTION:
kollins.homelinux.com.  60      IN    A       71.34.72.206

;; AUTHORITY SECTION:
homelinux.com.          85698   IN    NS      ns1.dyndns.org.
homelinux.com.          85698   IN    NS      ns2.dyndns.org.
...
darin@linux:~$ dig -x 71.34.72.206
...
;; QUESTION SECTION:
;206.72.34.71.in-addr.arpa.     IN    PTR

;; ANSWER SECTION:
206.72.34.71.in-addr.arpa. 86400 IN   PTR     71-34-72-206.ptld.qwest.net.

;; AUTHORITY SECTION:
72.34.71.in-addr.arpa.  86400   IN    NS      authns2.dnvr.qwest.net.
72.34.71.in-addr.arpa.  86400   IN    NS      authns3.sttl.qwest.net.
72.34.71.in-addr.arpa.  86400   IN    NS      authns1.mpls.qwest.net.
...
Amazon has reverse lookup PTR records for their IP address(es) that point to their domain name, because their service provider gives them control of, or allows them to request changes to, the DNS for their IP address(es)

I, on the other hand, have control of my forward dynamic DNS but even if I wanted it, Qworst wouldn't change the DNS PTR records for my IP address(es).
 
Old 01-07-2006, 05:13 AM   #5
shadowsa
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thank you i understand this totally, but this is exacly the reason why sorbs does not want to delist me from their dynamic blacklist, im listed there as dynamic, actually it seems like the whole addressrage is listed. so how do you solve that issue?

thank you very much in advance
 
Old 01-11-2006, 06:10 PM   #6
Darin
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From http://www.us.sorbs.net/
Quote:
Dynamic IP users, please note, SORBS is not identifying you as a spammer. SORBS is identifying you as a Dynamic IP address user, nothing more nothing less.
If that is as sincere as it sounds, then the problem of being blocked is in the mail admin who blocks everyone on the dynamic IP list. It also sounds like (http://www.us.sorbs.net/faq/dul.shtml) they have lists of dynamic IP addresses. Dynamic IP, as opposed to dynamic DNS, identifies you as a (usually) home user instead of a business with a dedicated server on a fixed IP address.

This means they will just have a list of ranges that ISPs assign to their [satellite/cable modem/dsl/dial-up] customers. It also means that even if you had a PTR record, your IP would still be on the list. The fix is to "buy" a static IP, this will probably cost many times more than what you currently pay for your home Internet connection. Another alternative is co-location, where you pay an ISP-like company to host your computer at their site.
 
  


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