Assign 3 Dynamic public IP

Hi.
This is my first Mikrotik router and my first post in this forum.
I did some research for my problem adn all I can find it’s how to assign 3 static Ip to 3 interfaces.
I have 3 Dynaminc IP that I want to assign to the WAN adn 2 other interface’s then I wan’t to assign rules for each interface.
Is that possible or I need static IP’s.
Until now I allways use Sonicwall but now I’m looking in to an alternative so I decide to test the Rb751g
Thank you guys

hi
your question is not clear.please send more info.

At the moment I have one Sonicwall using a WAN and OPT interface. The one has Dynamic public IP adress and the OPT has another public dynamic IP.
The third IP is setup wit a Netgear router.
Port 80 from first dynamic IP on sonicwall get redirect to server A. Port 80 coming to the second IP on the OPT port on the Sonicwall goes to server B and port 80 coming on the third IP assign to the Netgear goes to server C. It’s the same for all other ports. Ports 25 comes on IP one and goes to server A, port 6500 goes on IP two and FFW to server B and so on.
So basicly I need 3 interface to be dedicated to 3 public dynamic IP’s and redirect ports from there.
Now the Mikrotik has only one interface as a WAN or PoE and 4 as a LAN. So I want to set the WAN (poE) as interface one with public Dynamic IP, LAN Interface 2 as the second Dynamic public IP and LAN interface 3 as the third dynamic public IP and create rules between any of those interface and the remaining LAN interface (4 and 5)
Looks like if I go to the interfaces I can set it only as Static not as dynamic and they are LAN not WAN.