no, you can have as many as your router got enough port forwarding to support it. Even i don't use DCS2102 but this is how i setup for dcs-920 and dcs-2121
I will fix a static ip address for my ip camera from the camera network setting. Example if i got 3 camera. 192.168.1.20 / 192.168.1.21 / 192.168.1.22
Dlink camera normally also come with HTTP port input at the camera setup page. You can choose 6970 / 6971 / 6972
Next is your modem/router, open the 3 port for the 3 ip camera. Port forwarding setup.
=====================
Server Name = camera01
External Port Start = 6970
External Port End = 6970
Protocol = TCP
Internal Port Start = 6970
Internal Port End = 6970
Server IP Address = 192.168.1.20
=====================
Server Name = camera02
External Port Start = 6971
External Port End = 6971
Protocol = TCP
Internal Port Start = 6971
Internal Port End = 6971
Server IP Address = 192.168.1.21
=====================
Server Name = camera03
External Port Start = 6972
External Port End = 6972
Protocol = TCP
Internal Port Start = 6972
Internal Port End = 6972
Server IP Address = 192.168.1.22
=====================
To test your forward working, either get your current ip from router OR goto http://www.speedtest.net at the left side, there is your isp name and ip address, click on the ip address and you copy it. Paste in your browser and add port number.
Example: http://XXX.XX.XXX.XXX:6970 for camera 1
Example: http://XXX.XX.XXX.XXX:6971 for camera 2
Example: http://XXX.XX.XXX.XXX:6972 for camera 3
Finally you need setup your ddns so you don't to copy dynamic ip address provide by your isp. Most router also got a ddns setting. Read how to setup ddns from your router manual.
Example if set a ddns like mycamera.dlinkddns.com
To remote access you have to key in http://mycamera.dlinkddns.com:6970 for camera 1
To remote access you have to key in http://mycamera.dlinkddns.com:6971 for camera 2
To remote access you have to key in http://mycamera.dlinkddns.com:6972 for camera 3