Norton:
A – Security
Preferred DNS: 199.85.126.10
Alternate DNS: 199.85.127.10
B – Security + Pornography
Preferred DNS: 199.85.126.20
Alternate DNS: 199.85.127.20
C – Security + Pornography + Other
Preferred DNS: 199.85.126.30
Alternate DNS: 199.85.127.30
Comodo:
8.26.56.26
8.20.247.20
OpenDNS:
208.67.222.222
208.67.220.220
FamilyShield
208.67.222.123
208.67.220.123