Netfilter and virt-intall question in exam

I noticed the iptables question in exam about redirecting port from 80 to 8080. Not sure if I should nat with redirect or DNAT. I did redirect but specific --sport instead of --to-port. Course only shows --to-destination as example.
It accepted my command but I could not apply. After exam I tested on ubuntu VM and still got error apply as folder for network\xxx did not exist on \etc.

Another one is virt-install question which did not show osinfo with .img. I used --import -disk without OSinfo and I got stuck until I provided random CentOS version. Should I be using --OS-evironment generic instead?