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Route53 Hosted Zone, Reverse DNS, PTR, ddd.0/25.ccc.bbb.aaa.in-addr.arpa.
Posted by: tmuxr
Posted on: Sep 11, 2015 10:46 AM
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route53 , reverse_dns , arpa , in_addr , ptr , rfc_2317 , classless , cidr
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I have begun zone migration to Route53 from bind9 hosted in legacy environment.

I need to migrate a reverse lookup zone for a static public IPv4 subnet allocation.

It seems like Route53 is not properly supporting RFC 2317: Classless IN-ADDR.ARPA delegation

I'm looking for assistance getting this rDNS zone to function properly, and/or authoritative verification as to whether Route53 does in fact support RFC 2317.

Cross reference: I found another thread with similar question, Classless Reverse Map Delegation Issue

My allocation is a /25. Per RFC 2317, the zone should be declared as follows:

0/25.ccc.bbb.aaa.in-addr.arpa.


Within the zone, each PTR should have name ddd (the host address within the subnet) such that the record can be queried as

dig -t PTR ddd.0/25.ccc.bbb.aaa.in-addr.arpa.


In Route53 I created this zone. I observed that in the AWS web interface, the forward slash is displayed as an escaped octal ASCII character \057, as follows:

0\05725.ccc.bbb.aaa.in-addr.arpa.


Per my request, my ISP has maintained ARIN Reverse DNS Delegation with the name servers supplied by Route53 on the hosted zone:

ns-815.awsdns-37.net.
ns-1550.awsdns-01.co.uk.
ns-139.awsdns-17.com.
ns-1510.awsdns-60.org.


Indeed, if I query one of these authoritative nameservers for a PTR record within the hosted zone using the classful notation, I get the expected answer.

dig @ns-815.awsdns-37.net. -t PTR ddd.ccc.bbb.aaa.in-addr.arpa. +short
hostname.domain.tld


However, if I repeat the query to the same authoritative name server using RFC 2317 notation, I get no answer.

dig @ns-815.awsdns-37.net. -t PTR ddd.0/25.ccc.bbb.aaa.in-addr.arpa. +short


When I query other public nameservers with the classful notation (which is what will actually be happening in the wild), I get a CNAME in RFC 2317 classless notation, which then does not resolve to an FQDN.

dig @8.8.8.8 -t PTR ddd.ccc.bbb.aaa.in-addr.arpa.
CNAME ddd.0/25.ccc.bbb.aaa.in-addr.arpa.
 
dig @208.67.222.222 -t PTR ddd.ccc.bbb.aaa.in-addr.arpa.
CNAME ddd.0/25.ccc.bbb.aaa.in-addr.arpa.


So it seems like Route53 does support RFC 2317 in the sense that I can create a reverse hosted zone using the classless notation and then directly interrogate the authoritative name server using the classful notation,

but Route53 does NOT support RFC 2317 in the sense that it's not producing answers when interrogated using the classless notation.

Questions:

Have I made any mis-statements or omissions which bear on a solution to my problem?

Are any mistakes in configuration apparent, made by me or requested of my ISP by me?

Does Route53 in fact claim to or deny to support RFC 2317 classless notation?

Is anyone reading this thread in a position to provide further guidance?

Thank you very much for taking the time to read.

Regards,
Permlink Replies: 1 | Pages: 1 - Last Post: Sep 16, 2015 4:23 PM by: YuGu@AWS
Replies
Re: Route53 Hosted Zone, Reverse DNS, PTR, ddd.0/25.ccc.bbb.aaa.in-addr.arpa.
Posted by: YuGu@AWS
Posted on: Sep 16, 2015 4:23 PM
in response to: tmuxr in response to: tmuxr
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Hi tmuxr,

057 is the octal code for "/". If you try create a zone 0\05725.ccc.bbb.aaa.in-addr.arpa with us and add a PTR record ddd.0/25.ccc.bbb.aaa.in-addr.arpa. in that zone, it should work.

Thanks,

Yu