First let's make sure you understand what DNS is and how it works...
The Domain Name System (DNS) associates various information with domain names; most importantly, it serves as the "phone book" for the Internet by translating human-readable computer hostnames, e.g. www.example.com, into IP addresses, e.g. 208.77.188.166, which networking equipment needs to deliver information. A DNS also stores other information such as the list of mail servers that accept email for a given domain. By providing a worldwide keyword-based redirection service, the Domain Name System is an essential component of contemporary Internet use....
Now to answer your question...UltraDNS.
Quite specifically UltraDNS works exactly like DNS as explained above with one big exception. The DNS information provided from UltraDNS is filtered, put simply they explicitly remove DNS entries for ......Currently, we only block third-party verified sites that are potentially harmful to your computer. Typically, these are sites known to try and install viruses and other types of malware....Direct quote from UltraDNS--See Link Below.
I have utilized this type of DNS service in the past through opendns.com. I did notice a huge performance when I switched to opendns.com. In typing an address into my browser the page resolved and therefore loaded much quicker.
DNS is still subject to being hacked and so another alternative or additional measure it to utilize SpyBot's method. You can either control this manually or by loading SpyBot. Here is an excerpt from a blog regarding this type of protection...The fourth level of protection is through the addition of HOSTS file entries. This is a passive protection. The HOSTS file contains the mappings of IP addresses to host names and is loaded into memory at startup. The HOSTS file must contain one entry: "127.0.0.1 localhost". The IP address 127.0.0.1 is the local machine. Windows checks the HOSTS file before it queries any DNS (Domain Name System) servers, which enables entries in the HOSTS file to override addresses in the DNS. Adding an entry such as “127.0.0.1 malware.com” to the HOSTS file prevents the access of “malware.com” through IE because any connection attempts are redirected back to the local machine. HOSTS file entries can also be used to block other applications from connecting to the Internet.
One last thing, you might be wondering or asking yourself, My ISP probably does all this for me so why would I even bother? Well there are no ISP's that I know of that filter or block out certain DNS entries, if they did it would definitely help with virus and malware infections.