[CentOS] What can I do to UNDERSTAND why I can't reach centos.org (but everyone else can)?

Thu Feb 28 20:54:37 UTC 2013
Rock <RockSockDoc at gmail.com>

On Thu, 28 Feb 2013 13:40:55 -0500, m.roth-x6lchVBUigD1P9xLtpHBDw wrote:

> Could you define "me"? Are you using this at home, or at work? What kind
> of connection? If this is work, are you paying for a fixed IP?

I have a fixed IP address at home.

> I get to 20 (except for me it's 15), and www.centos.org is
> the next hop (16).

After hashing this out on alt.comp.freeware all morning, 
someone surmised that my static public IP address might
have been added to a blocklist in the past few days, 
either by the penultimate hop or by centos.org itself. 

So, the question morphs to whether or not we have tools at
our disposal which can pinpoint which entity is blocking my 
IP address? 

Note: I left a phone message at the DNS registrant for 
the penultimate hop and I left an email for the centos.org
webmaster.

> have you compared the contents of /etc/resolv.conf now, 
> and again when centos.org isn't visible?

Well, I must admit I never even knew that file existed.
Here is what it has in it:

$ cat /etc/resolv.conf
  # Generated by NetworkManager
  nameserver 192.168.1.1