Juergen,
You seem to have gotten the scenario just right; one NAT NIC for accessing the internet, one HostOnly NIC for Host-to-Guest communications.
xtrailrunner wrote:So DNS resolution could become a problem
No, not at all. The DNS information is populated from the host. And the host get that "variable" information based on its environment. So, if you're at location A, with a LAN range of 10.0.0.x and DNS from your ISP's defaults, but then you move to location B, with a LAN range of 192.168.2.x, and DNS set to 1.1.1.1, your host is going to be happy, right? Well, so will be your guests, if you leave everything to the defaults.
If you put the guests to sleep, you might have issues until it re-synchronizes , but you might have had those issues with a physical computer as well.
xtrailrunner wrote:which IP address is recommended for the fixed IP address of the network card associated with the host-only adapter
You can select anything you choose really. If you have only 1 VM, then (by default) the IP is going to be 192.168.56.101 (the first available DHCP address, check your HostOnly DHCP server). If you want to have it fixed, just pick 192.168.56.50, no one is going to complain...
However, while testing this on my Win host, I noticed something interesting; the HostOnly IP for the host, was set as 169.254.x.y. That's an APIPA address. I don't remember that being the case! And I have no clue when that changed! Before it used to be that the host's HostOnly IP was 192.168.56.100, and the DHCP server was set to give IPs from .101 to .254. Something changed in there and I've missed it (?).
Anyway since the situation is as is, I'd suggest editing the HostOnly properties and "fix" your IPs:
- 192.168.56.40 (fixed) for the host, configurable from the HostOnly properties (choose "Configure Adapter Manually").
- 192.168.56.50 (fixed) for the guest, configurable from within your guest.