You are troubleshooting reported connectivity issues from remote users who are accessing corporate headquarters via an IPsec VPN connection. What should be your first step in troubleshooting these issues?

A.
issue a show cryptoisakmp policy command to verify matching policies of the tunnel endpoints

B.
ping the tunnel endpoint

C.
run a traceroute to verify the tunnel path

D.
debug the connection process and look for any error messages in tunnel establishment