On Tue, 17 May 2005, Sam MacDonald wrote:

>   the external address assigned by your ISP 172.16.5.47

This is RFC 1918 space, the ISP appears to be doing NAT.

>      you can NOT get to it using this address
>      I can't ping this address and the address times out using Firefox
>      trace route dies at c6400-nrp-3.border.mpls.visi.com

This is probably your first hop through VISI's network that speaks BGP. 
172.16/12 won't appear in the global routing table, so it (correctly) 
drops your packets on the floor.  ON THE FLOOR MAN!!!  :)

What I gathered from the original post is that he has a public IP of 
63.something, which is being NAT'd to 172.16.something by the ISP.  He 
can't get to 63.something internally, since that's a public IP somewhere 
on his ISP's network, so it must route outside of his net.  Then it gets 
to the ISP's network and gets dropped (whatever device won't route packet 
back the same interface they came in, or something similar).

Without a diagram and more details, I would have to agree with Josh and 
say that if all he's trying to accomplish is to have an easy hostname to 
use to get to it, a static entry in hosts for his internal machines sounds 
like the best option.

If this doesn't work, I've got another option brewing in the back of my 
mind, but Randy would have to have a router on his network that he 
controls, and could add an IP or route to.