So we have an ubuntu server running DHCP & DNS managed through webmin (because it's less effort )
Nothing is BROKEN, but I noticed duplicate leases showing. Anyone know why and how I can prevent that from happenning?
e.g. this android phone shows twice
10.56.9.120 90:21:55:c9:4b:75 android_200142972d3b1451 2012/01/19 06:17:25 2012/01/19 07:17:25
10.56.9.120 90:21:55:c9:4b:75 android_200142972d3b1451 2012/01/19 06:47:23 2012/01/19 07:47:23
this iMac shows twice :
10.56.9.70 c4:2c:03:06:87:87 host3 2012/01/19 05:58:55 2012/01/19 06:58:55
10.56.9.70 c4:2c:03:06:87:87 host3 2012/01/19 06:28:55 2012/01/19 07:28:55
this laptop shows 4 times, twice for LAN and twice for Wireless
10.56.9.87 ac:81:12:13:a5:ff host4 2012/01/19 06:14:34 2012/01/19 07:14:34
10.56.9.47 1c:75:08:56:72:ba host4 2012/01/19 06:14:35 2012/01/19 07:14:35
10.56.9.87 ac:81:12:13:a5:ff host4 2012/01/19 06:44:34 2012/01/19 07:44:34
10.56.9.47 1c:75:08:56:72:ba host4 2012/01/19 06:44:35 2012/01/19 07:44:35
Best Answer
Its normal behavior, and in your case you see different lease times too. Instead of constantly rewriting the entire leases file the dhcp daemon just appends to the end. When it restarts it reads the last records for each entry to build its active database.
Check the second paragraph under the Format topic at dhcpd.leases(5) manpage:
http://linux.die.net/man/5/dhcpd.leases