81.21.143 is a class C of IPs

Sample IPs from the class C 81.21.143

81.21.143.31	View precise location of 81.21.143.31 on the map!
81.21.143.144	View precise location of 81.21.143.144 on the map!
81.21.143.127	View precise location of 81.21.143.127 on the map!
81.21.143.102	View precise location of 81.21.143.102 on the map!
81.21.143.59	View precise location of 81.21.143.59 on the map!
81.21.143.215	View precise location of 81.21.143.215 on the map!
81.21.143.85	View precise location of 81.21.143.85 on the map!
81.21.143.15	View precise location of 81.21.143.15 on the map!
81.21.143.184	View precise location of 81.21.143.184 on the map!
81.21.143.243	View precise location of 81.21.143.243 on the map!
81.21.143.228	View precise location of 81.21.143.228 on the map!

10 Random IPs

145.237.98.239	Find precise map location of 145.237.98.239
164.242.240.34	Find precise map location of 164.242.240.34
222.210.175.6	Find precise map location of 222.210.175.6
91.63.2.7	Find precise map location of 91.63.2.7
69.195.54.8	Find precise map location of 69.195.54.8
198.37.45.190	Find precise map location of 198.37.45.190
169.137.103.250	Find precise map location of 169.137.103.250
46.162.155.122	Find precise map location of 46.162.155.122
184.106.184.10	Find precise map location of 184.106.184.10
156.75.64.143	Find precise map location of 156.75.64.143
75.140.7.191	Find precise map location of 75.140.7.191

TestURI.org is a free web-sniffer.net alternative. It alows you to send custom HTTP request and check the HTTP response.