I believe I should be assigning DNS to my VPN clients as show below

group-policy IGBVPN attributes
dns-server value a.b.c.d a.b.c.d

vpn-idle-timeout 600
default-domain value igb.illinois.edu

However when I connect, the client does not get those dns addresses when I do an  ipconfig /all, even though the IP address is properly assigned.

   DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1
                                       fec0:0:0:ffff::2%1
                                       fec0:0:0:ffff::3%1

I would normally expect to see the ip addresses specified in the dns-server area above.  What am I missing, and what is the proper way to debug this?

Dan