[arin-tech-discuss] zero-padded IP addresses in "startAddress" and "endAddress" values

David Huberman dhuberma at arin.net
Wed Mar 28 15:40:20 EDT 2012

Hello Dani,

ARIN's Registration RESTful web service has always expressed IP addresses
with zero padding. As you point out, however, the Whois RESTful web
service does not.  I think a fair explanation of these two behaviors is
that Whois is assumed to be read mostly by humans, and in contrast, the
output of the Registration RESTful web service is assumed to be
interpreted by machines.

We do note that the Payloads documentation currently available does not
properly indicate that the output is zero padded. We have a documentation
refresh coming very very shortly, and we will work to correct this


David R Huberman
Principal Technical Analyst, ARIN

On 3/28/12 1:46 PM, "Dani Roisman" <droisman at softlayer.com> wrote:


One of our developers just pointed out to me that the values for
"startAddress" and "endAddress" values are now zero padded.  Is it
possible this was a result of the Mar 24th code push
  If so - was this expected, or a bug?

Here's an example from query "curl -4
https://www.arin.net/rest/net/NET-75-126-0-0-1?apikey=<snip>" (note, the
API key must be authorized to the network owner if you're trying to
reproduce this, try your key and your netblock)

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<net xmlns="http://www.arin.net/regrws/core/v1">
<pocLinkRef handle="IPADM258-ARIN" function="N" description="NOC"/>
<pocLinkRef handle="IPADM258-ARIN" function="T" description="Tech"/>
<pocLinkRef handle="ABUSE1025-ARIN" function="AB" description="Abuse"/>
<description>Direct Allocation</description>
<endAddress></endAddress>    <--- this line
<startAddress></startAddress>    <--- and this line
<registrationDate >2006-05-12T17:11:04-04:00</registrationDate>

Note that this *differs* from public whois output, for example that same

Using " curl -4 http://whois.arin.net/rest/net/NET-75-126-0-0-1"

<?xml version='1.0'?>
<?xml-stylesheet type='text/xsl'
href='http://whois.arin.net/xsl/website.xsl' ?>
<net xmlns="http://www.arin.net/whoisrws/core/v1"
<endAddress></endAddress> <-- this is what is expected
<description>Direct Allocation</description>
<startAddress></startAddress>  <-- this is what is expected
<orgRef name="SoftLayer Technologies Inc."
<parentNetRef name="NET75"

Dani Roisman
VP, Network Operations
droisman at softlayer.com
(281) 714-3714 direct
(818) 481-5581 cell

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