So we talked about IP addresses, we talked about how to turn a domain name into an IP address… so the next question is, how do we get there from here?  I mean, how does my computer access that domain that I want to see?  Well, it’s called routing or taking a route.

When I leave my house and go to the comic book store, I take a route.  I can go down back roads or main roads or even sneak through back alleys if I’m walking.  I could even take a detour through the Batcave (if I knew where it was) or sneak through Stark Enterprises (If I knew where that was!).

But I’m lazy.  Taking all those detours or back alleys or even back roads is just the long way and I really want to get there as quick as possible.  I want the latest Spiderman, please, or the latest Wonder Woman.  I don’t want to spend all my time getting there.

Well, the Internet works the same way.

When you go from your computer to www.google.com, you send your traffic on a route through the Internet.  That route takes you through various computers with a special tasks, known as routers.  You hop from one router to the next until you reach that magic destination.  Which is kind of why each step is known as a hop.  Think of it as a magical rabbit carrying your information from one computer to the next until he reaches his rabbit hole.  Or don’t, that’s rather silly.

Of course, there’s a command to see those hops.  It’s called traceroute.

You can run this from your command like:

Alpha:~ computerlamp$ traceroute www.google.com
traceroute to www.google.com (172.217.4.164), 30 hops max, 60 byte packets
 1 ip-69-163-160-1.dreamhost.com (69.163.160.1) 2.273 ms 2.246 ms 2.229 ms
 2 pdx1-cr-1.sd.dreamhost.com (66.33.200.2) 0.211 ms pdx1-cr-2.sd.dreamhost.com (66.33.200.3) 0.229 ms 0.268 ms
 3 pdx1-bdr-2.sd.dreamhost.com (66.33.200.1) 0.239 ms pdx1-bdr-1.sd.dreamhost.com (66.33.200.0) 0.234 ms 0.262 ms
 4 pdx1-bdr-1.sd.dreamhost.com (66.33.200.0) 0.248 ms google.nwax.net (198.32.195.34) 5.565 ms pdx1-bdr-1.sd.dreamhost.com (66.33.200.0) 0.215 ms
 5 google.nwax.net (198.32.195.34) 5.589 ms 6.025 ms 108.170.245.114 (108.170.245.114) 5.611 ms
 6 209.85.248.159 (209.85.248.159) 6.152 ms 108.170.245.98 (108.170.245.98) 5.733 ms 66.249.94.201 (66.249.94.201) 6.185 ms
 7 209.85.250.126 (209.85.250.126) 8.912 ms 72.14.238.38 (72.14.238.38) 9.633 ms 209.85.250.126 (209.85.250.126) 8.765 ms
 8 74.125.37.136 (74.125.37.136) 30.852 ms 30.771 ms 209.85.250.126 (209.85.250.126) 8.087 ms
 9 209.85.248.124 (209.85.248.124) 30.571 ms 74.125.37.136 (74.125.37.136) 29.833 ms 209.85.247.0 (209.85.247.0) 29.980 ms
10 108.170.247.129 (108.170.247.129) 31.130 ms 209.85.247.0 (209.85.247.0) 30.637 ms 30.647 ms
11 108.170.247.161 (108.170.247.161) 31.333 ms 31.123 ms 108.170.247.129 (108.170.247.129) 30.494 ms
12 108.170.234.215 (108.170.234.215) 30.513 ms lax28s01-in-f164.1e100.net (172.217.4.164) 30.423 ms 108.170.234.213 (108.170.234.213) 30.562 ms

That’s twelve hops to get there from here!

Or I could use what is called a Looking Glass Utility and do it on a webpage.  Global Crossing has such a Utility.  This lets you see the route from somewhere else, rather than from your computer.

traceroute doesn’t always work.  Sometimes companies block the kind of traffic that traceroute uses.  Try using it to go to www.marvel.com and see what happens!  If you