A single-ended path is one that is monitored in only one direction: source to target. A dual-ended path is one that is monitored independently in both directions; for this the path must have one AppNeta monitoring point as the source and another as the target. Monitoring in both directions is useful for paths that have links that are known to be asymmetric, like the connection to your ISP, or where the path is equally burdened in both directions, like for video conferencing and voip.
Under the hood, there is a further difference between single- and dual-ended paths, which explains why they have different capabilities. Single-ended monitoring involves sending a train of ICMP echos to the path target and measuring various aspects of the packets received in response. Network devices and end-stations generally respond to ICMP echos, which is why a monitoring point isn’t required at the far end. The trade off is that there is no monitoring point then to initiate inbound diagnostics. Dual-ended monitoring on the other hand uses UDP. UDP isn’t purpose-built for discovering and announcing network presence like ICMP, so an AppNeta monitoring point is required at the far end to respond to UDP probes.
Because these two path types use different protocols and your network might treat those protocols differently, it’s possible that their respective performance metrics might not match.
On a dual-ended path, the monitoring method is the same in both directions, but there might be an impact on diagnostics depending on which monitoring point is designated the source.