dhcpinform request from Vista gets wrong Name servers
Randall C Grimshaw
rgrimsha at syr.edu
Wed Aug 15 17:39:32 UTC 2007
I will answer my own question. After defining teredo.ipv6.microsoft.com in the captive DNS server, Vista no longer requests Name servers in the option list of the followup dhcpinform packet, and works correctly with the captive DNS Name server.
; these are the vista dhcpinform solution
teredo.ipv6.microsoft.com. IN A 188.8.131.52
teredo.ipv6.microsoft.com. IN A 184.108.40.206
teredo.ipv6.microsoft.com. IN A 220.127.116.11
teredo.ipv6.microsoft.com. IN A 18.104.22.168
teredo.ipv6.microsoft.com. IN A 22.214.171.124
teredo.ipv6.microsoft.com.yourdomain.edu. IN A 126.96.36.199
teredo.ipv6.microsoft.com.yourdomain.edu. IN A 188.8.131.52
teredo.ipv6.microsoft.com.yourdomain.edu. IN A 184.108.40.206
teredo.ipv6.microsoft.com.yourdomain.edu. IN A 220.127.116.11
teredo.ipv6.microsoft.com.yourdomain.edu. IN A 18.104.22.168
From: Randall C Grimshaw
Sent: Wed 8/15/2007 12:05 PM
To: dhcp-users at isc.org
Subject: dhcpinform request from Vista gets wrong Name servers
We run a network where dhcp gives unknown machines an address and configuration different by subnet from known machines.
DNS is one of these subnet based configurations that is given based on access to the pool granted by access permissions of known.
The DNS server for unknown systems resolves most addresses to a registration web server.
The Vista machines initially get the correct DNS settings and query for isatap (which resolves to the registration system) then queries for teredo.ipv6.microsoft.com (which resolves to the registration system).... then the rub... the Vista machine will perform a dhcpinfo query for name servers among other things and get the default name servers in the dhcpack - the default (production) name servers cannot be reached from the captive subnets and wouldn't direct users to the registration system if they were.
I am not sure if this is a bug in ISC dhcp by RFC or not.
Does snyone know if the dhcpinfo is a response to unexpected answer to the other two queries?
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