[c-nsp] DHCP Binding Expiration

[Church, Charles]

Interesting.  Might be fun (in a dorky networking kind of way) to look
at a packet capture of it.  Maybe the client doesn't like the lease
time, or it's tied into DDNS somehow.  I looked a bit, and found in the
RFC (http://www.faqs.org/rfcs/rfc2131.html) a blurb about lease times:

"The client may ask for a
   permanent assignment by asking for an infinite lease.  Even when
   assigning "permanent" addresses, a server may choose to give out
   lengthy but non-infinite leases to allow detection of the fact that
   the client has been retired. "

I've seen those infinite leases before, never cared enough to look into
it.  Might be interesting to find out why though...

Chuck 

-----Original Message-----
From: Justin Shore [mailto:justin at justinshore.com] 
Sent: Monday, February 09, 2009 2:11 PM
To: Church, Charles
Cc: Manaf Al Oqlah; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] DHCP Binding Expiration


Church, Charles wrote:
> Aren't those BOOTP clients that don't understand the concept of an
> expiration? 

Once when I was curious (and very bored) I tracked a couple of them 
down.  One was a Windows XP machine and the other was a fairly new 
D-Link router/firewall CPE (which we have hundreds on our network).  I 
don't know if either of them support Bootp but I would expect this 
problem to come up more often if that was the case.  I'm trying to think

of what our customers would have on our edges that would support Bootp. 
  Nothing comes to mind.  I'm sure you can configure some older clients 
to do Bootp of course (Macs still support it if you intentionally 
configure it that way) but no major demographic comes to mind.  I can 
certainly be missing something though.

Justin