Bind9 + DHCP - very few forward map updates, lot of reverse updates?

rylan76 · 11-27-2012, 12:26 AM

Hi guys

I'm running bind and dhcpd on Centos 6.

Keys are correctly setup between the two servers, the DHCP server successfully updates the named daemon's forward and reverse zones.

However, by scrutinizing the /var/log/messages I'm seeing about 90% of the mappings taking place from the DHCP server are for the reverse (in-addr.arpa) zone only, and for about 10% of the DHCP requests both zones get mapped.

So some machines will not resolve to their names, because DHCP only mapped them to the in-addr.arpa zone - in reverse. Others (about 10%) DO get mapped to both zones as they should, and their names therefore resolve.

The network was managed until a day previously by a Windows 2000 server that was doing DHCP and DNS duty, this has now been taken over by the Centos 6 setup I put together.

Is this due to the fact that leases granted by the Windows machine haven't expired yet on the Windows clients on the network (change took place a day ago) - and where I see forward AND reverse mapping is only when the "new" Linux DHCP server on my Centos box is actually allocating addresses?

An example of a map going "correcty" - forward and backward maps added:

Code:

Nov 26 11:36:36 domain.com dhcpd: Added new forward map from userlaptop.domain.com to 172.16.2.11
Nov 26 11:36:36 domain.com dhcpd: added reverse map from 11.2.16.172.in-addr.arpa. to userlaptop.domain.com
Nov 26 11:36:36 domain.com dhcpd: DHCPREQUEST for 172.16.2.11 from 24:b6:fd:37:8f:95 via eth0
Nov 26 11:36:36 domain.com dhcpd: DHCPACK on 172.16.2.11 to 24:b6:fd:37:8f:95 (userlaptop) via eth0

An example of a map NOT going correctly - only a reverse map added - why?

Code:

Nov 26 13:07:59 domain.com dhcpd: DHCPRELEASE of 172.16.1.151 from 50:e5:49:46:c8:e1 (USER-PC) via eth0 (found)
Nov 26 13:08:05 domain.com dhcpd: DHCPDISCOVER from 50:e5:49:46:c8:e1 via eth0
Nov 26 13:08:10 domain.com dhcpd: DHCPOFFER on 172.16.1.151 to 50:e5:49:46:c8:e1 (USER-PC) via eth0
Nov 26 13:08:10 domain.com named[5001]: client 127.0.0.1#54468: signer "rndc-key" approved
Nov 26 13:08:10 domain.com named[5001]: client 127.0.0.1#54468: updating zone '16.172.in-addr.arpa/IN': deleting rrset at '151.1.16.172.in-addr.arpa' PTR
Nov 26 13:08:10 domain.com named[5001]: client 127.0.0.1#54468: updating zone '16.172.in-addr.arpa/IN': adding an RR at '151.1.16.172.in-addr.arpa' PTR
Nov 26 13:08:10 domain.com dhcpd: added reverse map from 151.1.16.172.in-addr.arpa. to USER-PC.domain.com
Nov 26 13:08:10 domain.com dhcpd: DHCPREQUEST for 172.16.1.151 (172.16.1.1) from 50:e5:49:46:c8:e1 (USER-PC) via eth0
Nov 26 13:08:10 domain.com dhcpd: DHCPACK on 172.16.1.151 to 50:e5:49:46:c8:e1 (USER-PC) via eth0

A short log sample of general DHCP / Named activity:

Code:

Nov 27 08:08:15 domain.com dhcpd: DHCPINFORM from 172.16.1.65 via eth0
Nov 27 08:08:15 domain.com dhcpd: DHCPACK to 172.16.1.65 (14:fe:b5:a0:5b:55) via eth0
Nov 27 08:08:20 domain.com named[7182]: client 127.0.0.1#40421: signer "rndc-key" approved
Nov 27 08:08:20 domain.com named[7182]: client 127.0.0.1#40421: updating zone '16.172.in-addr.arpa/IN': deleting rrset at '73.1.16.172.in-addr.arpa' PTR
Nov 27 08:08:20 domain.com named[7182]: client 127.0.0.1#40421: updating zone '16.172.in-addr.arpa/IN': adding an RR at '73.1.16.172.in-addr.arpa' PTR
Nov 27 08:08:20 domain.com dhcpd: added reverse map from 73.1.16.172.in-addr.arpa. to user2-PC.domain.com
Nov 27 08:08:20 domain.com dhcpd: DHCPREQUEST for 172.16.1.73 from 84:8f:69:b7:d0:dc via eth0
Nov 27 08:08:20 domain.com dhcpd: DHCPACK on 172.16.1.73 to 84:8f:69:b7:d0:dc (user2-PC) via eth0
Nov 27 08:08:24 domain.com dhcpd: DHCPREQUEST for 172.16.1.73 from 84:8f:69:b7:d0:dc (user2-PC) via eth0
Nov 27 08:08:24 domain.com dhcpd: DHCPACK on 172.16.1.73 to 84:8f:69:b7:d0:dc (user2-PC) via eth0
Nov 27 08:08:25 domain.com dhcpd: DHCPINFORM from 172.16.2.11 via eth0
Nov 27 08:08:25 domain.com dhcpd: DHCPACK to 172.16.2.11 (24:b6:fd:37:8f:95) via eth0
Nov 27 08:08:30 domain.com dhcpd: DHCPREQUEST for 172.16.1.73 from 84:8f:69:b7:d0:dc (user2-PC) via eth0
Nov 27 08:08:30 domain.com dhcpd: DHCPACK on 172.16.1.73 to 84:8f:69:b7:d0:dc (user2-PC) via eth0
Nov 27 08:08:30 domain.com dhcpd: DHCPINFORM from 172.16.1.85 via eth0
Nov 27 08:08:30 domain.com dhcpd: DHCPACK to 172.16.1.85 (00:1c:c0:ee:b6:4e) via eth0
Nov 27 08:08:31 domain.com dhcpd: DHCPINFORM from 172.16.1.219 via eth0
Nov 27 08:08:31 domain.com dhcpd: DHCPACK to 172.16.1.219 (00:1c:c4:24:de:8e) via eth0
Nov 27 08:08:35 domain.com dhcpd: DHCPINFORM from 172.16.1.55 via eth0
Nov 27 08:08:35 domain.com dhcpd: DHCPACK to 172.16.1.55 (00:11:09:2a:af:1c) via eth0
Nov 27 08:08:37 domain.com dhcpd: DHCPINFORM from 172.16.1.128 via eth0
Nov 27 08:08:37 domain.com dhcpd: DHCPACK to 172.16.1.128 (00:11:85:79:f0:fd) via eth0
Nov 27 08:08:42 domain.com smbd[14151]: [2012/11/27 08:08:42.424528,  0] lib/util_sock.c:1626(get_peer_name)
Nov 27 08:08:42 domain.com smbd[14151]:   Matchname failed on AJS-NB.domain.com ::ffff:172.16.1.232
Nov 27 08:08:46 domain.com dhcpd: DHCPREQUEST for 172.16.1.73 from 84:8f:69:b7:d0:dc (user2-PC) via eth0
Nov 27 08:08:46 domain.com dhcpd: DHCPACK on 172.16.1.73 to 84:8f:69:b7:d0:dc (user2-PC) via eth0
Nov 27 08:08:48 domain.com dhcpd: DHCPINFORM from 172.16.1.129 via eth0
Nov 27 08:08:48 domain.com dhcpd: DHCPACK to 172.16.1.129 (14:fe:b5:a0:5c:fa) via eth0
Nov 27 08:08:49 domain.com dhcpd: DHCPREQUEST for 192.168.0.101 from 4c:80:93:2d:65:95 via eth0: wrong network.
Nov 27 08:08:49 domain.com dhcpd: DHCPNAK on 192.168.0.101 to 4c:80:93:2d:65:95 via eth0
Nov 27 08:08:49 domain.com dhcpd: DHCPDISCOVER from 4c:80:93:2d:65:95 via eth0
Nov 27 08:08:49 domain.com dhcpd: Abandoning IP address 172.16.2.20: pinged before offer
Nov 27 08:08:54 domain.com dhcpd: DHCPDISCOVER from 4c:80:93:2d:65:95 via eth0
Nov 27 08:08:54 domain.com named[7182]: client 172.16.1.73#60090: update 'domain.com/IN' denied
Nov 27 08:08:54 domain.com dhcpd: DHCPINFORM from 172.16.1.221 via eth0
Nov 27 08:08:54 domain.com dhcpd: DHCPACK to 172.16.1.221 (00:1a:4b:43:f9:7e) via eth0
Nov 27 08:08:58 domain.com dhcpd: DHCPINFORM from 172.16.2.10 via eth0
Nov 27 08:08:58 domain.com dhcpd: DHCPACK to 172.16.2.10 (78:e4:00:18:c0:ed) via eth0
Nov 27 08:08:58 domain.com dhcpd: DHCPINFORM from 172.16.1.93 via eth0
Nov 27 08:08:58 domain.com dhcpd: DHCPACK to 172.16.1.93 (00:26:2d:9e:ba:5a) via eth0
Nov 27 08:08:59 domain.com dhcpd: DHCPOFFER on 172.16.2.21 to 4c:80:93:2d:65:95 (user2-PC) via eth0
Nov 27 08:08:59 domain.com named[7182]: client 127.0.0.1#43848: signer "rndc-key" approved
Nov 27 08:08:59 domain.com named[7182]: client 127.0.0.1#43848: updating zone '16.172.in-addr.arpa/IN': deleting rrset at '21.2.16.172.in-addr.arpa' PTR
Nov 27 08:08:59 domain.com named[7182]: client 127.0.0.1#43848: updating zone '16.172.in-addr.arpa/IN': adding an RR at '21.2.16.172.in-addr.arpa' PTR
Nov 27 08:08:59 domain.com dhcpd: added reverse map from 21.2.16.172.in-addr.arpa. to user2-PC.domain.com
Nov 27 08:08:59 domain.com dhcpd: DHCPREQUEST for 172.16.2.21 (172.16.1.1) from 4c:80:93:2d:65:95 (user2-PC) via eth0

It also appears that the machines that are being mapped forward AND backward correctly are Windows XP machines, but Windows 7 machines only get mapped backward - can this be accurate / true?

Any input appreciated!

Thanks,