Amazon Network Support Engineer interview questions

1. what is the difference between a router and a switch ? 2.what is the difference betwwen UDP and TCP ? 3.explain to me DHCP and DNS ? 4.on which layer of the OSI model is the a network cable ? 5. what is the Spanning tree protocol ? 6.on which layer is a switch and a router located of teh OSI model ? 7.on which layer of the OSI model is VLAN ? 8. how do you move a file from one directory to the other in linux ? 9. how do you change the permission of a user to execute permission ?