Can I install windows via external harddrive on to a newly built pc!?

[PCNIGHTMARE]

Hi my pc build is done now i want to install a operating system,

first question do i need internet connection to install windows etc cos i dnt have a wireless wifi adapter and lan is not an option cos im upstairs.

second question can I use a external harddrive of 1 tb to install windows on my pc cos i tried to use mediaextractiontoolkit that i downloaded of microsoft.com but it wont recognize my external harddrive....is the stupid little usb stick rlly the only option!?
DO i nrlly need to buy it just to install windows!?

 

[Colif]

You don't need internet to install it, just to update and activate it later.

you can only install off a USB or DVD, external hdd won't work as its not an expected path and the installation is likely to bug out when it restarts.

If this is a new motherboard and CPU etc then yes, you have to buy it to install windows. If iits an upgrade of a previous install of win 10 and you didn't replace motherboard, then you can reinstall it for free.