- A. The link between Host1 and Switch1 is down.
- B. TCP/IP is not functioning on Host1
- C. The link between Router1 and Router2 is down.
- D. The default gateway on Host1 is incorrect.
- E. Interface Fa0/0 on Router1 is shutdown.
- F. The link between Switch1 and Router1 is down.
Host1 tries to communicate with Host2. The message destination host unreachable from Router1 indicates that the problem occurs when the data is forwarded from Host1 to Host2. According to the topology, we can infer that The link between Router1 and Router2 is down.