Can you install windows 10 with an external cdr/dvd drive?

Yes, I can install windows 10 with an external cdr/dvd drive. I am using windows 10.

Yes you can, but Windows 10 has now exceeded the capacity of a DVD, so if you are looking to install Windows 10 from a optical medium, you might want to use a bluray disc to store Windows 10 on.

Yes, I have installed windows 10 last 2 years ago.

Yes that or just use a standard USB thumb drive, which is what I do always since I don't either use optical drives on my PCs. ...

ask microsoft , they wrote it so they decide if it is bootable of cdrom and usb , seems its only bootable of one hard drive , after all you registered it for 1 computer didnt you . Simply no you cant .

As long as you can boot to the DVD, you can install from it.  If the computer does not automatically boot to DVD, you'll need to change boot settings, usually by pressing F2 or DEL or some other key as soon as the computer is turned on.

Be aware that the 64-bit version of Windows 10 is more than 5 GB, so if you planned to burn your own DVD, it will need to be a dual-layer or Blu-ray.  If you have a DVD from Microsoft, you're all set.

If your computer did not come with a DVD drive, it's probably a newer computer, which is good, because then it will boot to a USB flash drive.  An 8 GB USB stick is plenty large enough to hold the Windows install image, and you can get a drive that size for a song.

from such a drive, yes.  to such a drive?  no

Yes, you can. However before you can you have to do two things:

1. Create a bootable DVD with a proper Windows 10 image file on it2. Set in your BIOS to boot off of the external drive (if capable)

Of course you can when you do the boot menu which is f12 on a Dell or f9 or f11 on Hewlett-Packard and you look on the boot menu you're going to look for the external USB device which will be listed arrow down to it and select it and you will boot to it just like you would if the CD or the DVD was built in.

I'd like to remind you that you can make a flash drive for free with the Windows 10 media installation tool and that it's much faster than using a DVD or a CD

Yes ... but only if your computer allows booting from an external CDR/DVD Drive.  You'll need to check in your system BIOS/UEFI to see if that functionality is available to you.  (Watch your screen/monitor when you first boot up your computer and you'll see which key you need to press to enter BIOS/UEFI.  Most commonly, this would be Del or F2, but some motherboards have a different key for you to press.)