- It fails-unsafe. If your external IP changes and not immediately updated in OpenDNS then all previously blocked sites become available
- It logs all your DNS requests by default.
- It can be easily circumvented, by simply pointing at a different DNS server (188.8.131.52 anyone?) instead of using the DNS provided by DHCP
- It’s owned by Cisco. Cisco is known to have had many issues with securing their stuff
A better alternative is to have an internal DNS blackhole, like pi-hole