Top questions for switching !

1. What is switching?
2. Explain Ethernet Header?
3. What is ARP?
4. Explaining what is Proxy ARP, Gratuitous ARP, and Reverse ARP?
5. What are the types of ARP packets?
6. Explain ARP Header?
7. Explaining end to end flow of ARP?
8. Explain the ARP table?
9. What are the important codes of ICMP?
10. Hubs belong to one collision domain. Why?
11. How are collision and broadcast domains defined in a L2switch?
12. What is the standard range of VLANs? What is an extended range of VLANs? What are the reserved VLANs? When to use standard and extended VLANs?
13. Why is the maximum number of VLANs 4096?
14. What is the use of Management VLAN?
15. What is a Native VLAN and why is it used? Do we need Native VLAN in new networks and how to disable it if not needed?
16. How to configure interfaces in VLANs?
17. How does the switch store all VLAN information?
18. What is an access port?
19. What is a trunk port?
20. Types of frame tagging protocols?
21. Explain diff between ISL and 802.1q ?
22. Explain 802.1q header?
23. Explain ISL header?
24. How to configure access port and a trunk port?
25. Troubleshooting trunk , what parameters should match on both sides of the trunk?
26. What is VTP? Difference between VTP version 1,2,3?
27. What are VTP different modes?
28. What is a revision number and how to change a revision number when implementing a old switch in net network topology?
29. What is VTP pruning?
30. What are the advantages of linkgroups?
31. What are the max number of links supported on a linkgroup when manually configured?
32. What are max number of linkgroups supported on a switch?
33. What are the match criteria for ether channel ports to be actve?
34. Explain load balancing on etherchannel?
35. Explain load balancing in etherchannel when source IP is used and when destination IP is used?
36. Why do we use dynamic link aggregation protocol when we have a manual configuration possible?
37. Which IP address and MAC address are used for link group?
38. What is LACP
39. What is the advantage of LACP? 8 ports as active and 8 ports as standby.
40. How LACP works? How to decide which ports are active and which are standby?
41. How to configure VRRP?
42. Explain Packet of VRRP advertisement?
43. How to load balance using VRRP?
44. How pre-emption works in VRRP?
45. What MAC address is used in VRRPs Virtual IP address?
46. How does VRRP advertisements work?
47. Explain the states of VRRP?
48. How to implement switch port security?
49. What is the use of private VLAN?
50. What are the types of secondary VLANs?
51. How to configure Private VLANs?
52. What is DHCP spoofing? How is it implemented?
53. What are Dynamic ARP inspections and how is it implemented?
54. Explain ways of inter-VLAN communication?
55. What is used by STP to build its topology?
56. How often are BPDU sent out? To which address? On which interfaces?
57. Explain the STP convergence process?
58. Does STP support a backup root bridge?
59. What is root secondary?
60. Explain STP convergence with 3 switch, 4 switch and 5 switch diagram?
61. Explain the STP port states?
62. Explain STP timers? Explain why they are used and what is the default value of each?
63. Explain BPDU packet format?
64. Explain BPDU message types and when they are used?
65. BPDU Flags?
66. Explain How STP converges? 1) if direct topology change 2) indirect topology change 3) if insignificant topology change . Explain with diagram of three switch and 5 switch. What happens if a root port goes down? What happens if the designated port goes down?
67. How to improve STP convergence times? 1) Port fast(blocking to forwarding direct and no TCN bpdu generated ) 2)uplink fast(forwarding delay eradicated by keeping standby port) 3) backbone fast (max age is eradicated)
68. How will you protect against unexpected loss of BPDU?
69. Explain RSTP port roles?
70. Explain RSPT port states?
71. Explain RSTP types of Ports ?
72. Explain RSTP convergence process?
73. Explain how RSTP handles Topology change?
74. Difference between RSTP and STP?
75. Explain MSTP .
76. What is Multi VLAN port ?
77. What is QinQ ( 802.1Q tunneling ) ?
78. Explain Dynamic Trunking Protocol (DTP)
79. What is VLAN Hopping?
80. Explain Unidirectional Link Detection (UDLD)

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