option 51 ' dhcp-lease-time' vs other lease time statements

Aaron Bennett abennett at clarku.edu
Tue Sep 19 14:46:41 UTC 2006


I'm working on a large script to migrate from win2k dhcp to isc dhcp.  ( 
the one in contrib doesn't work on win2k, the registry stuff changed 
from nt4 )

Each scope from Win2K ( in isc terms, 'pool') defines option 51.  They 
call it "Lease" and describe it as "Client IP address lease time in 
seconds", but it's option value is 51 which is 'dhcp-lease-time' in isc 
and rfc world.  The isc dhcp.conf examples I've seen, rather then using 
option dhcp-lease-time, use 'default-lease-time,'  'max-lease-time,' and 

What's the difference?  What exactly does option 51 do and how does that 
compare to the other ways to specify a lease time?  What I'm looking for 
is the migrate the exact _intent_ of the Win2K configuration 
intelligently into isc-world.

( I'll contribute the script back to isc when it's done -- finished 
product will handle both config & lease database )


Aaron Bennett

Aaron Bennett
Sr. Unix Systems Administrator
Clark University ITS
abennett at clarku.edu     |     508.781.7315

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