DNS problem with Mac OS X 10.6 and later

Banana Flex flex.banana at bluewin.ch
Fri Dec 10 17:02:54 UTC 2010

hello list,

Our setup:

- a MAN network with thousand of Mac computers running Mac OS X 10.4, 10.5 and 10.6
- two linux servers running dhcp-3.1.3ESV and bind-9.5.0P2, redundant as a cooperation, this is the main DHCP/DNS servers for the MAN
- a multitude of servers running Mac OS X Server (10.4, 10.5, 10.6) for our clients, not centralized, connected to the MAN
- 13 DNS zones
- HSRP network by Cisco with circa 20 loop of a 23-bit range address (ex. :,,, .../23), that is the MAN

Each clients computers are connected to the centralized DHCP/DNS Linux server's and are registered in the zone with the DynamicDNS function.
We use the DHCP Client ID (option 61) of the service to redirect and register the client computer into the good domain

The linux servers are in the main domain city.educational, at the first level, it's IP addresses is and
All others zones are in the form: department.city.educational

All clients machines are in DHCP. Servers are in DHCP with a statically assigned address

The problem:

On 10.5 computers, all are still okay, you can found all records using the host command and ping them:

$ hostname

$ host 002378
002378.department.city.educational has address

$ host domain name pointer 002378.department.city.educational.

$ ping -c3 002378
PING 002378.department.city.educational ( 56 data bytes
64 bytes from icmp_seq=0 ttl=64 time=0.547 ms
64 bytes from icmp_seq=1 ttl=64 time=0.512 ms
64 bytes from icmp_seq=2 ttl=64 time=0.482 ms

--- 002378.department.city.educational ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.482/0.514/0.547/0.027 ms

$ cat /etc/resolv.conf 
domain department.city.educational
search department.city.educational city.educational department.city.educational

on 10.6 computers, you can host but the ping does not work

$ host 002378
002378.department.city.educational has address

$ ping 002378
ping: cannot resolve 002378: Unknown host

This mean that you can not resolve 002378 without his FQDN

Graphically example is the "Connect to Server" window form the Finder with the short name of the server resulting in a failed connection.

On a 10.6, a printer like 500265 (FQDN = 500265.department.city.educational) does not print if you not utilize the FQDN. On 10.4 and 10.5 all this work

If you setup your 10.6 clients statically with the DNS, example with the following command line:
networksetup -setsearchdomains Ethernet department.city.educational city.educational
the problem disappaers and all is okay

If you read the /etc/resolv.conf from a 10.4, 10.5 or 10.6 clients, all lines are the same ! in DHCP setup or statically setup,
on a linux box is the same result !

I think Mac OS X 10.6 not interpret correctly the domain search from a DHCP server because all others systems work well

Please let me know if anyone in the list have the same problem or a workaround
Help are welcome

Thank you for reading

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