What is difference from Reverse DNS Lookup - Reverse IP Lookup
<p>When using websites that retrieve <em>all|</em> domain names associated to an IP address, What is the difference between Reverse DNS Lookup and Reverse IP Lookup? </p>

<p>These two procedures show different outputs.
The reverse dns lookup is based from PTR records dns, generally show less result than ip lookup. But not ever the PTR record are present.</p>

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<p>[EDIT]</p>

<p>DNS REVERSE LOOKUP (74.208.56.223):</p>

<pre><code>223.56.208.74.in-addr.arpa domain name pointer perfora.net.
</code></pre>

<p>IP REVERSE LOOKUP (74.208.56.223):</p>

<pre><code>andrewslist.org 2016-03-05
awppwlocal5.org 2016-03-05
belgerado.com   2016-02-01
blet301.com 2016-03-11
camasbiz.com    2016-02-01
camassmokeshop.com  2016-02-01
canhazcode.com  2016-02-01
capturedmemoriesbyjb.com    2016-02-01
creativemediatechniques.com 2012-11-12
culturalimmersions.com  2012-11-12
easywifihotspot.com 2012-11-12
emeraldtree-inc.com 2016-02-01
epharma360.com  2016-02-01
erosionguardproducts.com    2016-02-01
execusummit-registration.com    2016-02-01
fatboyzsports.com   2016-02-01
firedistrict23.com  2016-02-01
hawkeyebars.com 2012-11-12
historybooksource.com   2016-02-01
hr-execusummit.com  2016-02-01
illuminatingeyes.com    2012-06-29
insidescooponrealestate.com 2012-11-12
inst-for-ip.org 2015-04-03
kylehalloutdoors.biz    2016-03-05
kylehalloutdoors.com    2015-11-14
kylehalloutdoors.info   2016-03-08
kylehalloutdoors.net    2016-03-01
kylehalloutdoors.org    2016-03-05
kylehalloutdoors.us 2016-03-08
lakesidebrewer.com  2015-11-14
lakesidebrewingco.com   2015-11-14
letters2home.com    2015-11-14
litgationsymposium.com  2015-11-14
noraparksgroup.info 2016-03-08
northslopewriters.com   2015-11-14
occursillo.org  2016-02-26
pawlek.com  2015-11-14
pinedecline.com 2015-11-14
pinggemporium.com   2015-11-14
riafunda.com    2015-11-14
savvysoccer.com 2015-11-14
schavonephotography.com 2015-11-14
schiavonephotography.com    2015-11-14
shadesofsoul.info   2015-10-20
shorelinecomputerservices.com   2015-11-14
sirclesaver.com 2012-06-29
specializedsafetytraining.com   2015-11-14
specializedsafetytraining.net   2016-03-01
swaramanthra.com    2015-03-23
teachbytech.org 2016-02-26
tofinocoffeecompany.com 2012-11-12
w3colors.com    2015-11-14
</code></pre>

<p>Why the info obtained from reverse ip lookup are not present in DNS records? How to obtain this info the ip reverse lookup if them not present in DNS records?
With input an ip address I want in output all hosts associated with it.</p>