Dynamic dns and Rogue Clients

Martin McCormick martin at dc.cis.okstate.edu
Mon Jun 24 19:04:12 UTC 2002

	We are testing dynamic dns using bind9.2.1 and
dhcpd-3.0.1RC9.  Everything works as advertised which brings me
to the problem.

	We deliberately set two Windows systems to use the same
net-bios name in the same default TCP/IP domain so their names
would be duplicates.

	The first system booted and got registered with a proper
forward and reverse record in DNS.  The second system got what we
really don't like to see at all, namely a working TCP/IP stack,
an IP number from the dhcp server, but no dns records of any

	The dhcp documentation says this will happen if dhcpd
can't register the A and PTR records.

	Is there a way to cause bind to automatically generate
an A and PTR record for this address containing some unique

	What I did for now was to stuff a generic host name in to
all the addresses in the dhcp range.  This makes all of them
reverse map for the benefit of any software that gets upset if
this can't be done.  When a system that is not having any problem
registers, the update replaces the generic name with the system's
net-bios name as expected.  I will still have to go through the
ranges at regular intervals and replenish the generic addresses
when somebody leaves a vacant address, but I am always looking
for something more elegant and automatic so that the
house-keeping does itself.

	I have a copy of DNS and BIND 4TH Edition on order, but
right now, all I have is the 3RD edition and a lot has changed.

Martin McCormick 405 744-7572   Stillwater, OK
OSU Center for Computing and Information services Network Operations Group

More information about the bind-users mailing list