Part 4 – Wide Area Networks

Implementing Point-to-Point WANs

  1. What is a leased circuit?
  2. What does CSU/DSU do?
  3. What is DCE and DTE?
  4. What is HDLC?
  5. What is PPP?
  6. Which 2 authentication protocol does PPP have?
  7. How do you configure the more secure PPP auth?

Continue reading “Part 4 – Wide Area Networks”


Part 3 – IP Version 4 Routing Protocols

Implementing OSPF for IPv4

  1. What are the steps of becoming an OSPF neighbor?
  2. What are the OSPF states?
  3. What does a hello packet consists of?
  4. What parameters have to match in the hello packet to form neighborship?
  5. When OSPF electing the router ID why are loopback interfaces preferred?
  6. Why is it good to configure the router ID manually?
  7. How do neighbors exchange their LSDB? (detailed)
  8. Which neighbor sends its DD first?
  9. How is the Link-state Database maintained?
  10. Why are Designated Routers needed? What do they do?
  11. Why do we need areas?
  12. What is ABR and ASBR and why are they special?
  13. What LSA types do you know about?
  14. How does SPF decides the best route if there are more route to a subnet?
  15. How does OSPF elects the DR?

Continue reading “Part 3 – IP Version 4 Routing Protocols”

Part 1 – LAN Switching

Spanning Tree Protocol

  1. Why do we need STP? How does it work? (brief)
  2. What happens if a link fails in a topology where STP is active?
  3. How does STP work? (detailed)
  4. What are the 3 port types at spanning tree?
  5. What does a BPDU consist of?
  6. What is the root bridge?
  7. What is a Bridge ID?
  8. Which port will be blocked on a line?
  9. What if there is 2 switches with 2 links between them (equal)? Which port will STP block?
  10. Why do we have to modify the default root bridge selection process?
  11. What are the default port costs of STP?
  12. What are the STP timers?
  13. What is an EtherChannel?
  14. What is PortFast? Where should we use it?
  15. What is a BPDU guard?
  16. What is the improvements of RSTP? What new port type does it have?

Continue reading “Part 1 – LAN Switching”

Part 4 – Implementing IP Version 4

Operating Cisco Routers

  • What is CEF?
  • What interface status codes do you know about?
  • What happens if the host on the left side pings ( no static or dynamic routing configured)routing1
  • Why is it good to add Source IP to a ping?
  • What is a default route and how do you define one?
  • What happens if the router have 2 static (or connected) routes to a destination? Which one will it choose?
  • How does Auxiliary port work?
  • What is CEF?
  • What are the options for routing between subnets on VLANs?
  • How does Router on a Stick works? (explain routing)
  • What are the steps of creating sub interfaces on router on a stick?
  • How do you configure the native VLAN on a trunk?
  • What is needed for routing between VLANs on a L3 switch?
  • What is a secondary IP good for?
  • How do you define a static route?
  • What is the difference between the next hop IP and the outgoing interface command?
  • What is a default route and why do we need it? (How do you configure it?)

Continue reading “Part 4 – Implementing IP Version 4”

Part 2 – Ethernet LANs and Switches

Building Ethernet LANs with Switches

  • What are Hubs used for?
  • What are the drawbacks of the hubs?
  • What is CSMA/CD and how does it work?
  • What are Bridges used for?
  • How many collision domains do a switch create?
  • What is ASIC?
  • What is the difference between Collision domain and Broadcast domain?
  • What is the broadcast MAC address?
  • What is the MAC table (or CAM table) used for?
  • How does a switch find out which port is for a given MAC?
  • What is the inactivity timer (aging timer) and how does it work?
  • What are the 3 types of a switch’s internal processing?
  • What are the drawback of broadcast?
  • What is a LAN?
  • What is the access, distribution and core layer in switching?
  • What is IEEE autonegotiation? What is the problem with Hubs?
  • What is the difference between multi-mode and single-mode fiber?

Continue reading “Part 2 – Ethernet LANs and Switches”

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