8.8.4.4

Interpreted as: What DNS Server is 8.8.4.4?

8.8.4.4 is the secondary DNS server for Google Public DNS.

Google Public DNS is a global DNS service that is run by Google for the purpose of making the Internet and the DNS system faster, safer, secure, and more reliable for everyone online. This service is available for anyone to use, and is often faster and more reliable than using the DNS servers that your own ISP allocates to you.

More information on Google Public DNS and what 8.8.4.4 is for, check out the Google DNS page.