Yes, public IP (shared with tons of users in your warehouse) -> NAT -> private static IP. It doesnt download using your static IP. Your public IP may be 119.xxx.xxx.xxx which the company bought, and like what hawkeye said, may be used by someone. You will use that 119. ip to download and make contact with the internet instead of your private static ip which may be 220.127.116.11 which you have and may seems impossible for others to have it. It's a subnet for your company to communicate within yourselves. Hope it's layman enough.