12.04 – Sudo can not resolve host localhost.localdomain

hi Guys

When I run

sudo nano /etc/proftpd/proftpd.conf

I get this error:

Sudo can not resolve host localhost.localdomain

I try to sit down DefaultRoot to / var / wwwas in the following screenshots.

nano_screenshot

When I press CTRl + X then write Y and press Enter / kbd>. There is this mistake

errors_screenshot

Can someone please tell me how I can solve this problem?