Where to place the Spanning Tree Protocol Root Switch (Root Bridge)
In a default Spanning Tree Protocol (STP) configuration network, a Switch with the lowest MAC address will be elected as the Root Bridge (Root Switch)
This is because, Spanning Tree Protocol (STP) will select a Bridge with lowest Switch ID (Bridge ID) as the Root Bridge (Root Switch) . Bridge ID consists off two parts, and they are 1) Switch Priority and 2) MAC address.
The default value for Switch Priority is 32768 in all the Switches. Therefore, the switch with the lowest MAC address will become the Root Bridge (Root Switch).
If all the Switches in Spanning Tree Protocol (STP) have the same Spanning Tree priority, the switch with the lowest MAC address will become the Root Bridge (Root Switch). Typically older switches have lower MAC addresses, and by default, there is a chance for an older Switch to become a Root Bridge (Root Switch). An older Switch may not have enough memory or hardware capacity to perform as a Root Bridge (Root Switch).
Root Bridge (Root Switch). must be placed in a central part of the network, to provide the best possible data path. Root Bridge (Root Switch) must be placed near to Network Servers and other important devices which are the sources of high network traffic to ensure that the topology of the network is optimized to the traffic flows of the network.
Normally, Switches operating at the Distribution Layer is configured as the Spanning Tree Root Bridge (Root Switch), because Switches operating at the Distribution Layer typically do not connect to end devices. Access Layer network changes are less likely to affect Switches operating at the Distribution Layer.