ISP customer assignments

Ricky Beam jfbeam at
Wed Oct 21 21:37:02 UTC 2009

On Tue, 20 Oct 2009 19:38:58 -0400, Bill Stewart <nonobvious at>  
> ... If you've got a VPN tunnel device, too often the remote
> end will want to contact you at some numerical IPv4 address and isn't
> smart enough to query DNS to get it.

As I was told by Cisco, that's a security "feature".  Fixed VPN endpoints  
are supposed to be *fixed* endpoints.  Yes, it is a pain when an address  
changes, for whatever reason.  But relying on DNS to eventually get the  
endpoint(s) right is an even bigger mess... how often is the name<->IP  
updated? how often do the various DNS servers revalidate those records?  
how often do the VPN devices revalidate the names? what happens when the  
dns changes while the vpn is still up?

I'll stick with entering IP addresses.


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