Trying to identify hosts

We get lots of probes from subdomains of southwestdoor.com and
secureserver.net 's SOA and I'm curious who these guys are?

The only web page I could find was southwestdoor redirects to
http://www.arcadiacustoms.com and then to http://arcadia-custom.com/
(a hardware company is causing unwanted network traffic - not unless
they're owned)

Traceroute for southwestdoor.com goes through secureserver.net and
they have lots of references (in dns) to themselves, jomax.net and
domaincontrol.com.

Can someone give me a better picture of how this all fits together on
a company level - as in how do these guys make money and why are they
probing our network? I understand scans from ISPs and colos, but I
can't directly identify these guys as either.

Ok, got a few off list replies that secureserver.net is godaddy which
is fine - makes sense. I just wish this would link back to them easier
(some backup ns being something.godaddy.com or some SOA of an IP
listed in the spf being something.godaddy.com or whatever).

Thank y'all for the info.

Oh and along that line of trying to find the source - nothing
indicates godaddy here (kinda annoying):

% curl -I secureserver.net

        ~ swlap1
HTTP/1.1 301 Moved Permanently
Cache-Control: no-cache, no-store, must-revalidate
Pragma: no-cache
Content-Length: 145
Expires: 0
Location: http://www.secureserver.net/
Server: Microsoft-IIS/7.0
P3P: policyref="/w3c/p3p.xml", CP="COM CNT DEM FIN GOV INT NAV ONL PHY
PRE PUR STA UNI IDC CAO OTI DSP COR CUR OUR IND"