:Try clicking on the Whois link at the bottom of an IP user's talk page  that tells you the ISP. Then click on the traceroute link. The traceroute results show the route a packet takes to the customer; while you can't decode all the results, you can usually get useful info you can interpret: 
 :*   •  • [/wiki/Special:Log/move?user= page moves] • block user • [/wiki/Special:Log/block?page=User: block log]): 
 :**hop 10 is the last hop with an identifiable location: gbr1-p70.dlstx.ip.att.net.  I figure that's Dallas, TX. The subsequent hops don't have geographic locations, but you can figure this person is in the Dallas region. 
 :**hop14 shows: 24-116-127-234.cpe.cableone.net. A quick trip to the cableone.net web site, http://www.cableone.net/about/locations.asp?STATE=TX, shows the company's Texas locations 
 :**Hop 14 + whois both confirm this is a cable modem customer. Those are not shared IPs (unless a neighbor's surfing on the subscriber's unsecured home Wi-fi!) 
 :*   •  • [/wiki/Special:Log/move?user= page moves] • block user • [/wiki/Special:Log/block?page=User: block log]): 
 :**Traceroute hop 13 was as far as the pings got before hitting a firewall  probably the user's.  "p9-0.dsl-06.dllstx.verizon-gni.net." can be interpreted to mean a DSL user in Verizon's Dallas region 
 :**Whois confirms it's a Verizon customer.  
 :**DSL accounts, like cable modem accounts, are almost never shared. 
 :Traceroute and whois data requires some interpretation and common sense. For instance, some Verizon IP addresses are still registered to GTE, Nynex or Bell Atlantic, 3 predecessor companies merged to form Verizon years ago. Another example: frequently the last 5 to 10 traceroute hops for some ISPs pass through hops with gobbledy-gook nomenclature you can't get a location out of. Some companies may mean a very narrow area in Dallas proper when they use dlstx; others may mean Texas + surrounding states. I've never seen that there's any standard nomenclature ISPs use when responding to traceroute pings; one may use dlstx, another rcntx (Richardson, a suburb), another dfw-1, still another wyqz for the same town. Just the same, common sense will get you far enough to figure out what you need to know. 

 :We already know this is almost certainly the webmaster for searchtexoma.com. Since their web site says they're based in Denison, Texas, about 65 miles northeast of Dallas, these results are no surprise. Had you seen, however, that the new IP address was in Singapore, or even just Atlanta, you'd want to check out the possibility it was an open proxy using a tool such as Completewhois. (Neither's an open proxy  I already checked). 

 :I hope this is helpful. Now that you know these IP addresses are not shared, I hope you will block them. It's what the policy calls for. 

 :Thanks for your help!