Hi,
I apologize for the delay in response.
The DNS lookup failed error is network issue and not an issue with Outlook.com.
I suggest you to refer to the responses Marked as answer in the following thread which discusses a similar issue.
Windows 7 DNS server not responding
Check if this helps in resolving the issue.
Hope this information is helpful. Please reply with the results and if you need further assistance or have any other queries regarding Windows, we are here to help you.