If you changed your DNS server list during the recent outage and would like to restore it to its original condition, then here are some links showing how to do that.
Typically your ISP provider determines the DNS server to be used. It is probably a good idea to stay with your ISP's choice of DNS server unless you fully understand the implications of changing it in your local settings.
Windows DNS Server Settings
Reference Win 7 Reference Win 8Win 10 link missing
Windows Summary: Control Panel > Network and Internet > Network & Sharing Center >
{select your connection} > Properties > Internet Protocol Version 4 (TCP/IPv4) >
Properties > Use the following DNS server addresses >
{edit DNS addresses} > OK > {OK out of remaining windows}
MAC DNS Server Settings
Reference Mac
Mac Summary:
System Preferences > Network > Advanced > DNS > DNS Servers >
{edit DNS addresses} > OK > Apply > Cmd-W