Top 100 Local Area Network (LAN) Interview Questions

Rashmi Bhardwaj | Interview Questions


  1. What is Local Area Network?
  2. What are different types of LAN topologies?
  3. Explain PING utility?
  4. What are different types of LAN devices?
  5. What is NETBEUI?
  6. What is NETBIOS?
  7. What is Subnet?
  8. What is MAC address?
  9. What is TCP/IP?
  10. What is difference between LAN and Private VLAN?
  11. What is a node?
  12. What is an IP address?
  13. What is ICMP?
  14. What is difference between static and dynamic IP addressing?
  15. What is DHCP? Why do so many LAN environment deploy DHCP servers?
  16. What are proxy servers and how do they protect computer networks
  17. What is TELNET?
  18. What is SSH?
  19. What is difference between TELNET and SSH?
  20. What is the maximum length allowed for a UTP cable?
  21. What is VPN?
  22. Which technical resource is responsible for day to day activities in LAN network like Operations support?
  23. What is the function of ARP in LAN?
  24. What is difference between ARP and RARP?
  25. What is a default Gateway and its use? Which devices can be configured as default gateway in a LAN network?
  26. What is difference between Hub and Switch?
  27. What is NIC?
  28. Which layer does Ethernet work on?
  29. What is CSMA/CD and CSMA/CA?
  30. What is Private IP address? What is the range of Private IP address?
  31. What does 10Base-T mean?
  32. What is tracert?
  33. Difference between straight though and crossover cable?
  34. What protocol does Ethernet work on?
  35. What is DNS?
  36. What is difference between TCP and UDP?
  37. What is Firewall?
  38. What is Difference between Domain and WorkGroup?
  39. An IP Phone and PC needs to be connected on LAN Switch. Both are in different Vlans. What configuration needs to be done on Switch to allow both devices to communicate through the Switch?
  40. A LAN Switch needs to be procured for terminating both IP Phones and PCs on each of port. What are the basic considerations while selecting the Switch?
  41. What is difference between Layer 3 Switch and Router?
  42. Define OSI reference model?
  43. A web server is installed inside the LAN environment to be accessed by local users. Generally which protocol and port number is used to access Web Server content?
  44. What is role of proxy server?
  45. What is significance of
  46. A new subnet (SVI = has been created on Layer 3 Switch where all the hosts in subnet will get IP from DHCP server which is in different subnet. What is the key configuration required on Core Switch to allow this communication to take place?
  47. A new Subnet needs to be created in LAN to allow approx. 300 end hosts in common Vlan (Broadcast domain). LAN administrator has a major IP pool of and needs to break the same to provide a segment best fit for new subnet.
  48. What are 3 types of transmission modes in between 2 devices?
  49. What is the maximum data transmission speed of Category 5, Category 5e and Category 6 UTP cable?
  50. How can communication across various VLANs be controlled in a LAN environment?
  51. What is the default encapsulation type of Ethernet interfaces on Cisco Routers?
  52. What is collision domain?
  53. Which class of IP address provides a maximum of only 254 host addresses per network ID?
  54. If a switch has 4 computers connected to it. There are no VLANs present. How many broadcast and collision domains is the switch creating?
  55. All LAN users are complaining of Internet not working. Hosts is LAN are part of Subnet with gateway configured as Gateway is the DSL Router (Mac Address A:A:A:A) which is directly connected to LAN switch from where it connects to all the end hosts. When the administrator issues command “arp –a” on one of the PC, the Physical address entry against is B:B:B:B. What could be the cause of Internet not working?
  56. Cite some services using TCP protocol?
  57. How many hosts IPs can be given from subnet
  58. What is broadcast domain?
  59. For the network, what is the broadcast address and how many are hosts?
  60. What is a network TAP?
  61. What is maximum length of Ethernet packet?
  62. What are sublayers of LAN layer?
  63. What is difference between unicast, multicast and broadcast?
  64. Where do we use Crossover cable?
  65. Define IEEE 802.3?
  66. In an existing 3 tier architecture, there is requirement for an additional LAN Switch for accommodating new joiner PCs. However, network architect shared a concern of overload on network. What do you think the network architect may be talking about?
  67. Which command is used to view the ip address and default gateway of a PC?
  68. What is difference between switch and bridge?
  69. What is difference between DOT1q and ISL encapsulation?
  70. Proxy ARP?
  71. How many wires does UTP cable has?
  72. LAN users accessing the Server-A are facing performance and slow access issue. On further troubleshooting, it was diagnosed that Uplink port between Core Switch and Server Switch is fully choked. What can be done to address this problem?

  73. In a Campus LAN setup where multiple buildings are being connected, a Ring topology is used across Switches (in Layer 2) in buildings. How many maximum switches (Buildings) can be connected in ring and why?
  74. What is the host range for the subnet on which the IP address resides?
  75. What is the maximum distance of UTP cable?
  76. Which connector UTP cable uses to connect with NIC?
  77. Where do we use Straight-through UTP cable?
  78. How often are BPDUs sent from a layer 2 device
  79. In a network with 10 switches, how many root switches will be there?
  80. Some new VLANs need to be configured in a switched network of multiple switches. This will consume a lot of manhours and management has called out for a solution to reduce time in creation and propagation of VLAN information across all switches. What would be the solution?
  81. What are the prerequisites to form an etherchannel?
  82. Customer LAN users were accessing WAN services through single WAN Router with Static Routing between Core Switch and WAN Router. However lately, considering the site criticality, another WAN Router is provisioned to provide WAN level redundancy in Active backup mode (Scenario 2).One challenge is that no change is allowed on Core Switch. What could be the best possible solution to address this condition?

  83. 2 VLANs are created on a Layer 2 Switch and 1 host is connected to LAN port of each VLAN. Somehow, these devices are not able to communicate to each other. What could be the reason?

  84. What does the error message of “hardware error” mean when we try to ping any ip from our desktop?
  85. How can we find the PC name which is part of same LAN .Only IP address of the device is given?
  86. Enlist some of the LAN troubleshooting utilities in DOS which are used in day to activities by network administrators?
  87. I am sitting on my PC inside LAN and browsing internet sites.How can I know the Private/Local IP address and Global IP used by my device to reach Internet?
  88. What is the smallest IPv4 subnet mask that can be applied to a network containing up to 30 devices?
  89. An access point without any external power source is connected to a LAN switch but does not power up.What could be the probable cause?
  90. A new Trunk Link Is Configured On a catalyst Switch. Do we need to allow VLANs over the trunk link?
  91. With a switch running Spanning-tree protocol, which types of ports don’t generate TCN ?
  92. Which VTP mode allows to change VLAN information on the switch?
  93. Portfast is configured on an end host connected port (port 10). A user who brought his own switch from home removes the end host machine and connects his own switch.This brings the network down. What could be the reason for this downtime?
  94. How can I find physical address of my LAN card?
  95. A new device is connected to LAN port of switch.Only information available is that device MAC address is CC:46:D6:AA:BB:CC.What can be inferred from this information?
  96. What si meant by VLSM?
  97. What is difference between baseband and broadband technology?
  98. A PC on port Fa0/0 of Switch needs to join multicast group What configuration is required on the port?
  99. What is difference between UTP and STP?
  100. What is FTP and what is it used for ?


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