Utilize traces ip routes

tracert.exe will allow you to trace the ip hops between your ip segment and the destination ip address. The basic syntax is simple:
tracert is-it-true.org
The above examines asks the network to send back information on the hops taken to get to address is-it-true.org. The results of the command from my workstation were:

Tracing route to is-it-true.org [204.117.195.207]
over a maximum of 30 hops:

  1   130 ms   140 ms   141 ms  max101.rcsntx.swbell.net [151.164.1.218] 
  2   140 ms   140 ms   140 ms  max-gateway.rcsntx.swbell.net [151.164.1.193] 
  3   140 ms   140 ms   140 ms  edge1-fa0-1-0.rcsntx.swbell.net [151.164.1.129] 
  4   130 ms   140 ms   140 ms  edge2-fa0-0-0.rcsntx.swbell.net [151.164.1.162] 
  5   181 ms   140 ms   140 ms  sl-gw13-fw-12-0-8xT1.sprintlink.net [144.228.137.41] 
  6   160 ms   181 ms   140 ms  sl-bb13-fw-2-2.sprintlink.net [144.232.11.61] 
  7   140 ms   141 ms   160 ms  sl-bb10-fw-5-2.sprintlink.net [144.232.11.169] 
  8   200 ms   181 ms   180 ms  sl-bb10-orl-2-0.sprintlink.net [144.232.9.106] 
  9   160 ms   181 ms   180 ms  sl-gw3-orl-0-0-0.sprintlink.net [144.232.2.150] 
 10   230 ms   201 ms   200 ms  sl-sprintfa-1-0-0.sprintlink.net [144.232.154.2] 
 11   220 ms   381 ms   240 ms  ias-wnpk-1.utelfla.com [207.30.208.1] 
 12   271 ms   220 ms   200 ms  router.cde.com [207.30.14.238] 
 13   201 ms   200 ms   200 ms  ns2.globalworks.net [204.117.195.207] 

Trace complete.

You may attempt to trace the route to certain sites and the trace will abort prior to reaching the requested site. Microsoft and others block ICMP packets arriving at its firewall. An additional eye-opener is how many hops there are between your site and the site you are attempting connection. Try the same command during different sessions and you will also find that the routes vary from session to session and from attempt to attempt.
tracert www.microsoft.com

Tracing route to www.microsoft.com [207.46.131.15]
over a maximum of 30 hops:

  1   150 ms   160 ms   140 ms  max100.rcsntx.swbell.net [151.164.1.200]
  2   140 ms   140 ms   141 ms  max-gateway.rcsntx.swbell.net [151.164.1.193]
  3   140 ms   140 ms   141 ms  edge1-fa0-0-0.rcsntx.swbell.net [151.164.1.161]
  4   140 ms   141 ms   140 ms  edge2-fa0-1-0.rcsntx.swbell.net [151.164.1.130]
  5   160 ms   161 ms   140 ms  sl-gw13-fw-12-0-8xT1.sprintlink.net [144.228.137.41]
  6   161 ms   140 ms   140 ms  sl-bb11-fw-2-2.sprintlink.net [144.232.11.65]
  7   200 ms   180 ms   200 ms  sl-bb10-sea-0-0.sprintlink.net [144.232.8.54]
  8   200 ms   220 ms   201 ms  sl-microsoft-4-4-0.sprintlink.net [144.232.192.6]
  9   201 ms   200 ms   200 ms  iuscgsrfec7501-a5-00-1.cp.msft.net [207.46.190.38]
 10   220 ms   220 ms   221 ms  icpmscomc7501-a0-00-1.cp.msft.net [207.46.129.3]
 11   200 ms   201 ms   200 ms  icpmscomc7501-a0-00-1.cp.msft.net [207.46.129.3]
 12     *        *        *     Request timed out.

The Request timed out. will occur randomly but when you get a series of these errors at the end of a tracert, it means the receiving router is blocking the ICMP packet returns.