Your ISP automatically assigns DNS servers when your router or computer connects to the internet via DHCP... but you don't have to use those. Below are free DNS servers you can use instead of the ones assigned, the best and most reliable of which, from the likes of Google and OpenDNS, you can find below:
|Provider||Primary DNS Server||Secondary DNS Server|
|Comodo Secure DNS||126.96.36.199||188.8.131.52|
Tip: Primary DNS servers are sometimes called preferred DNS servers and secondary DNS servers are sometimes called alternate DNS servers. Primary and secondary DNS servers can be "mixed and matched" to provide another layer of redundancy. In general, DNS servers are referred to as all sorts of names, like DNS server addresses, internet DNS servers, internet servers, DNS IP addresses, etc.