#A4# ## ## #HA server 1 Alice's house# ## ## #HA server 2 Bob's house # #network attack# ## ## #Observer# #Service is still up, attacker thinks it isn't hosted at Alice's# #ISP Layer# ## ## #HA server 1 Alice's house# ## ## #HA server 2 Bob's house # #network attack# ## ## #Observer# #ISP Layer# #Service is still up, attacker thinks it isn't hosted at Bob's#