There is a specific kind of panic that sets in when a legacy system crashes. You are staring at a server that has been humming along since the Obama administration, and suddenly, you need to reinstall. You have the license key taped to the side of the machine, but the install media? That’s gone.
If you are using an ISO for legacy lab or migration testing, ensure your environment meets these minimums: SQL Server 2008 R2 Requirements - ITPro Today 22 Feb 2012 — Sql Server 2008 R2 Iso