Comodo Secure DNS’s server infrastructure is spread around five continents, your DNS requests will be answered by the closest available set of servers. I swapped my ISP DNS for Comodo Secure DNS nearly a year ago and everything has always worked fine, I have never experienced any downtime and the DNS resolution speed is excellent.
When you come across a parked domain name Comodo Secure DNS will block it and warn that the page is parked, you will shown a Yahoo search box, the same blocking page will appear for 404 page not found URLs (typos, non existent domains), Comodo finances their free DNS service redirecting all 404 traffic to their Yahoo search, it is not intrusive and nobody forces you to use it. But not all parked domains are blocked, just a few number of them, my guess is that Comodo marks as parked all domains using DNS belonging to a domain parking company and if they don’t use it Comodo Secure DNS will not detect them, over 50% of parked domains get through their filter.
Comodo Secure DNS review conclusion
Setting up Comodo DNS is really simple, their site has easy to follow instructions with screenshots for all operating systems, I have run a benchmark on Comodo DNS service using NameBench and their servers get top results all the time. The only downside I see to Comodo Secure DNS is that their filtering of parked domain names should be optional and there is no way to change this.
Customization options for Comodo Secure DNS do not exist, if you need a family filter, you will be better off with OpenDNS.
Change DNS to get around ISP censorship
If you travel to a country that filters the internet, like China, Arabia Saudi or Australia, a VPN might not be enough to bypass ISP internet filtering and you will have to change the router Domain Name Servers given by the local ISP, it happened to one of my friends going to China for a week, Comodo Secure DNS together with VPN4ALL bypassed the Great Firewall of China but using only the VPN did not work.