As promissed, here is a small interview (24 questions) on basic Networking concepts – I thought of the questions myself and I did try to make some of them, slightly tricky. Also, some questions will require an open answer (no options to choose from)! So pay attention and comment on your answers; I will reply back to your registered email.

You will see few configuration commands which are specific to Cisco IOS though the concepts being tested, apply to other vendors as well.

Should you have any questions you would like to be part of the set, let me know.

So let’s start …

1. How would you configure a new Cisco router to assign an IP address to an interface and make it persistent between reboots? The router’s name is “Edge” and the router is in User mode (choose one best answer).

a) config t
interface fa0/0
ip address /30

b) en
config t
interface fa0/0
ip address

c) en
config t
interface fa0/1
ip address

2. What would you do to bring an interface up (choose all that apply)?

a) connect the cable at both ends
b) unshut the interface
c) change the cable
d) change the speed settings
e) change the duplex settings

3. How would you configure VLAN 100 on a switch as well as give the SVI for VLAN 100 an ip address?

a) (config)# interface fa0/0
(config-if)# ip address
(config-if)# switchport mode svi

b) (config)# interface fa0/0
(config-if)# ip address
(config-if)# switchport mode route

c) (config)# interface svi0/0
(config-if)# ip address

d) (config)# interface vlan 100
(config-if)# vlan 100
(config-if-vlan)# exit
(config-if)# ip address

e) (config)# interface vlan 100
(config-if)# ip address

4. What is the primary function of Spanning Tree (choose the best answer) ?

a) To avoid split-horizon
b) To avoid L2 loops
c) To create a tree
d) To mantain L3 loop-free topology

5. What is the advantage of MST over STP?

6. You have the following routes in your routing table on a router:

R /25 – fa0/0
O /24 – fa0/1

A packet arrives on interface fa0/2 addressed to – Which interface does the router forward the packet out, assuming Administrative Distance has not been altered?

7. A Cisco router is running latest IOS version and it has been confirmed that subnet-zero is allowed. Can you use the following configuration (yes/no)?

(config)# interface Fa0/0
(config-if)# ip address

8. What formula does OSPF use to generate its metric?

9. What do you need to configure under OSPF on a network containing links faster than 100 Mbps?

10. You have just configured a router and saved the configuration. When you reboot the router the running config is back to factory default configuration! What could be wrong?

11. You notice a lot of CRC errors on Fa0/0 on your router; what are some of the things you would check?

12. What is a passive interface in regards to OSPF?

13. What kind of neighbour authentication does OSPF support?

14. You open your browser and try to browse to where you host your CV. However, instead of your CV, you get a different page saying there could be an error. Discuss the following troubleshooting methodologies – which troubleshooting steps would you take matching each method?

a) Divide et Impera
b) Top-Down
c) Bottom-Up

15. ICMP is a Layer3 protocol (true/false).

16. When a (Layer3) packet travels through different Layer2 hops, the L2 address changes (true/false).

17. When a (Layer3) packet travels through different Layer2 hops, the TTL changes (true/false).

18. is part of the /28 subnet (true/false).

19. is a valid host IP; it is part of the /24 network

20. is a valid host IP; it is part of the /31 network

21. Which is the matching missing protocol or port number:

a) TCP/80
b) TCP/110
c) TCP/25
d) TCP/443
e) Telnet
f) SSH
g) DNS
h) UDP/500

22. Choose which of the following concepts apply to NAT (choose all that apply):

a) “Inside” mathes the local router interface facing the LAN
b) “Inside” matches the local LAN
c) “Outside” matches the WAN
d) “Outside” matches the local router interfaces facing the WAN
e) “Inside Local” is the LAN source IP Address, after translation
f) “Inside Local” is the LAN source IP Address, before translation
g) “Inside Global” is the source IP Address as shown on incoming packets
h) “Inside Global” is the source IP Address as shown on outgoing packets
i) “Outside Local” is the source IP Address an external device uses when it generates packets
j) “Outside Global” is the source IP Address as shown on incoming packets, before translation
k) “Outside Global” is the source IP Address as shown on incoming packets, after translation

23. Choose statements below which are true, regarding HSRP, VRRP and GLBP

a) HSRP and VRRP can be used for load-balancing, in a active-active setup
b) HSRP and VRRP can be used for load-balancing, in a active-passive setup
c) HSRP cannot be used for load-balancing; this is only available with GLBP in a active-active setup
d) GLBP can be used for load-balancing, though in a active-passive setup only
e) GLBP supports active-active configuration
f) VRRP and HSRP are open standards; there are minor differences between the two such as initial default settings

24. Two routers are setup with HSRP – one router goes down and the fail-over is successful; the failed router is successfully brought back online after 5 minutes however, a fail-back doesn’t occur. Why would this happen?


Thank you,
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