Secure DNS services are another method of blocking malware. A DNS service can provide real time domain blocking to prevent a user from visiting a known bad website. If a user attempted to go to that website the DNS service would not resolve that address, so that the user would not be able to visit it. The database of known bad websites are constantly updated on the DNS service.
The DNS service provider should be running on a secure platform to prevent someone from performing unauthorized altering of the DNS records.