Final answer:
The message will fail to arrive at its destination E if there are no alternative paths available when certain connections fail. Critical failures that prevent the message from reaching E include a complete disconnect from preceding points to C when C to E fails and when the only direct or indirect paths to D or E, such as A to B to C and A to D, are cutoff.
Step-by-step explanation:
The question concerns the ability to send a data packet across a network from Point D to Point E given certain connection failures. To determine under which circumstances the message will fail to reach its destination, one must understand the topology of the network and the available paths for data transmission.
- Failure C to E: If the connection from C to E fails, and there is no alternative path from C to E, the message will fail to reach E.
- Failure A to C: If A to C connection fails but there are alternative paths such as A to B to C or directly from A to D, then this failure does not necessarily result in communication failure, as long as there is at least one intact path to E.
- Failure A to C and B to C: If both A to C and B to C connections fail and there is no direct connection from A to B to C or A to D, then the message cannot reach C, hence it will not arrive at E.
- Failure A to D: If the direct connection from A to D fails, alternative paths including A to B to C to D must be considered. If no other path is available, the message will fail to arrive at E.
- Failure A to B and B to C: If both connections from A to B and B to C fail, and these are the only available paths from A to C, the message will not be able to reach C or D, and therefore will fail to arrive at E.