Yes, we were also having issues with a domain they manage. We got our first alert around 10am (14:02 UTC). Their own website was failing to load for me as well. I noticed at one point that they had modified the WHOIS record for markmonitor.com to add some extra authoritative name servers, and that seemed to make their website load again. Our apps came back shortly afterward.
We are not a direct customer, however, so I don't have a support contact to whom I can reach out.