I've experienced this too - I seem to get a few people joining my gameserver from that ISP and I notice the DNS appeared as 'localhost'. Not ideal and I imagine it could break certain things. I always assumed it was a misconfigured internet cafe or something. 'Nice' to know it's a wider issue
MAC addresses. HP-UX saves them in its startup configs for some reason. A place I worked at used a sample build for its 'gold' build. All builds had the same MAC. Hilarity ensued.
An alternative to typical configuration management (puppet, ansible, etc) is making your own OS installer. I've adapted the Ubuntu installer to turn a blank machine into a running instance of our app in just a couple of days. The client just has to pop-in the CD or flash drive, answer a couple of questions, and go grab a cup of tea while it installs.
You jest, but our previous "cloud" provider (which we used in 2012/13) took more than that to provision a bog standard Linux VPS - and they often got the distro wrong!
I can think of:
- Hostname conflicts
- SSH key duplication
- Driver issues if the hardware is not the same
Are there more?
This seems like a compelling argument for bootstrapping new instances with configuration management, rather than trying to re-use OS images.