well yes and no. Dynamic IP means your DNS server leases open IPs from a list. You could portforward one port, but you do not know if the same computer and IP will be leased.
Thus it's better to have a static IP so that the exact device can have its ports forward.
DNS server is usually your Router, or a computer that is a DNS server. You would change the ports that need to be forward in the router web settings. Usually 192.168.1.1 is your router.