Missing reverse DNS (PTR) for google IP addresses on route to ajax.googleapis.com

What steps will reproduce the problem?
1. On a computer in or near telenor's network in DK, do a traceroute
(traceroute or tracert OS command) to ajax.googleapis.com

2. Notice that many IP addresses listed on the route have no DNS name.

3. Use whois to determine that those IP addresses all "belong" to Google
Inc., and that the missing DNS entries are on Google's own DNS servers.

What is the expected output? What do you see instead?

Expected output:

  9    17 ms    17 ms    17 ms  ti3001b300-ae0-0.ti.telenor.net
[146.172.105.70]

 10    18 ms    17 ms    17 ms  somerouter123.xx.google.com [74.125.50.53]
 11    17 ms    17 ms    17 ms  somerouter234.xx.google.com [209.85.252.186]
 12    36 ms    36 ms    36 ms  somerouter345.xx.google.com [209.85.254.153]
 13    51 ms    51 ms    51 ms  somerouter456.xx.google.com [216.239.48.10]
 14    38 ms    39 ms    38 ms  somerouter567.xx.google.com [209.85.248.182]
 15    41 ms    49 ms    41 ms  somerouter678.xx.google.com [64.233.175.246]
 16    41 ms    40 ms    41 ms  somerouter789.xx.google.com [72.14.233.79]
 17    51 ms    54 ms    49 ms  somerouter890.xx.google.com [209.85.249.129]
 18    41 ms    41 ms    40 ms  nf-in-f95.google.com [64.233.183.95]
Actual output:

  9    17 ms    17 ms    17 ms  ti3001b300-ae0-0.ti.telenor.net
[146.172.105.70]

 10    18 ms    17 ms    17 ms  74.125.50.53
 11    17 ms    17 ms    17 ms  209.85.252.186
 12    36 ms    36 ms    36 ms  209.85.254.153
 13    51 ms    51 ms    51 ms  216.239.48.10
 14    38 ms    39 ms    38 ms  209.85.248.182
 15    41 ms    49 ms    41 ms  64.233.175.246
 16    41 ms    40 ms    41 ms  72.14.233.79
 17    51 ms    54 ms    49 ms  209.85.249.129
 18    41 ms    41 ms    40 ms  nf-in-f95.google.com [64.233.183.95]

What version of the product are you using? On what operating system?

Network behavior observed 2009-02-12 at 1:55 AM UTC

Tested using Windows XP, lack of entries on ns1.google.com verified
directly using Windows XP nslookup utility.

Please provide any additional information below.

I don't know about ARIN requirents, but RIPE traditionally imposes a
contractual requirement that all allocated actively used IP addresses
allocated from them to have valid DNS PTR records, and doing so is Internet
best practice anyway.

As makers of Google Earth, you may also wish to provide latitude/longitude
DNS records for your own computer names too, but this is quite optional.

records.

Original issue reported on code.google.com by moysulfi...@jbohm.dk on 12 Feb 2009 at 2:14

Raghuveersingh / google-ajax-apis

Missing reverse DNS (PTR) for google IP addresses on route to ajax.googleapis.com #199