Administer untrustd domain

I'm trying to administer users in an untrusted domain from my PC.

I use the below CMD line and I'm able to get ADUC running. Doing some tasks in ADUC, gives me the error "The specified domain either does not exist or could not be contacted."

C:\Windows\System32\runas.exe /netonly /user:UntrusedDomain\user"mmc dsa.msc /server=1.1.1.1"