I made a split DNS. An external DNS zone is arwal.com.pl , and internal DNS zone is intranet.arwal.com.pl . I am using DHCP. I set option 15 in DHCP ( DNS server ) to intranet.arwal.com.pl . In event log I have an error : 14120 The ISA server cannot create packet filter for xxx.xxx.xxx.xxx . The resolution for this error is in KB article Q288396 . But it doesn't works. Sincerely; Jacek