To reset the printer or to reset system or service defaults:
1. From the General Setup menu, click Resets.
2. To reset a service default, next to Reset Fax Defaults or Reset Scan Defaults, click Power
3. To reset a system default, next to Reset System Defaults or Reset Network Defaults, click
Power Off/On Printer.
4. To restart the printer without resetting any of the default settings, next to Power Off/On the
Printer, click Power Off/On Printer.
5. Click Save Changes.
Beyond that, there is nothing, DNS unknown doesn't even mean anything beyond that the printer isn't registered in the DNS server, which is typical when not part of a Domain. It does not mean it can't make a DNS connection or lookup. I can still scan via hostname.