Purchasing a PoE switch from Deep Sentinel or using an existing PoE switch with the DS Hub & DS Cameras are both OK.
Any PoE Switch is OK so long as there are enough PoE ports (one for each Camera)
- 4k dome uses the 802.3at standard
- 2k models are ok with 802.3af
If you have an existing switch (not PoE) you can use PoE injectors to add power rather than buying a new switch.