This happened yesterday morning also, DNS queries to .ws domains would result in NXDOMAIN. It also seemed intermittent - some clients would resolve names, some would not.

Edit: See also this thread on CloudFlare: https://community.cloudflare.com/t/certain-broadband-provide.... It appears the TLD DNS servers for .ws are having issues.

Edit 2: this is being tracked here: https://www.opensrsstatus.com/