Which of the following issues are created from redundant Layer-Two loops?

Redundant Layer-Two loops can cause broadcast storms, which occur when a broadcast frame circulates continuously between the switches in a looped topology. Each switch that receives the broadcast frame will forward it to all of its ports, which can result in the same frame being sent out repeatedly. This excessive transmission of broadcast packets can rapidly consume all available bandwidth on the network, degrading performance for all connected devices.

Broadcast storms can lead to network congestion, timeouts, and potentially make the network unusable if not mitigated. This issue is particularly prominent in networks that do not implement loop prevention technologies such as Spanning Tree Protocol (STP).

In contrast, while redundant setups can lead to routing loops and multiple frame copies, these are more typical issues associated with Layer-Three routing mechanisms instead. Voltage drops are not influenced by network topology in a way that would stem from Layer-Two loops. Thus, the primary concern directly related to redundant Layer-Two loops is indeed the formation of broadcast storms.