CCNP Interview Questions and Answers

Q1. What is the purpose of a default route?
A default route is used if there is not a specific entry in the routing table for the destination

Q2. How many VTP modes are there and what are they?
Three: Server, Client, and Transparent

Q3. What is the difference between acknowledgments and handshaking?
Handshaking is used to negotiate the properties of a connection that is being established. Acknowledgments are used to tell the sender that data has been successfully received by the destination during the use of a connection.

Q4. What does AAA stand for?
Authentication, authorization, and accounting

Q5. Describe why postal addresses and telephone numbers are routable.
A postal address has three components that can be used to deliver mail: state, city, and street. A phone number has an area code and exchange. At the core layer, mail can be delivered to the next post office based on only the state or city and state information. A phone number is delivered at the core layer based on the area code.

Q6. What are the purposes of areas in an OSPF network?
Areas allow the design of a hierarchical network. Routes can be summarized or blocked in an area to reduce the amount of routing information on internal OSPF routers

Q7. What is the difference between static routing protocol and dynamic routing protocol?

Static Routing Protocol Dynamic Routing Protocol
1. Best path is selected by network admin 1. By router
2. Requires less memory, cpu utilization 2. More
3. Topology changes are not automatic 3. Automatic
4. Secure 4. Less secure
5. Advertises indirectly connected networks 5. Directly connected networks
6. Implemented in smaller networks 6. large networks

Q8. Describe the difference between unicast, multicast, and broadcast traffic?
Unicast traffic flows from a single source to a single destination MAC address. Multicast traffic flows from a single source MAC address to many destinations and uses a functional MAC address. Broadcast traffic is from a single source to all devices on the Ethernet segment. This is specified by a destination MAC address of all ones.

Q9. What are the four different Ethernet encapsulation types?
From the Cisco IPX encapsulation command they are ARPA, NOVELL-ETHER, SAP and SNAP

Q10. What are the three main tasks of a transparent bridge?
Learning, Forwarding, Filtering

Q11. Difference between public ip address and private ip address?

Public IP address  Private IP address
1. Used for Internet access 1.  used within an organization
2. cannot use same ip address in different locations  2. possible
3. Assigned by IANA 3. Assigned by network administrator
4. Internet Routable on 4. Not routable on Internet

Q12. What does the term information hiding mean in relation to route summarization?
At the core layer in the postal system, the only information that is needed to make a routing decision is the state or city/state information. The specific street names and street numbers are hidden; the core layer does not need this information. At the core layer in the telephone system, the area code is used to make a routing decision. The specific exchange or last four digits of the phone number are not needed, or hidden, from the core layer.

Q13. What is Summarization?
Summarization is the process of combining two or more smaller networks into one large network.
There are two types of summarization
1. Auto Summary—done by router
2. Manual summary— done by network administrator

Q14. What is subnetting?
Subnetting is the process of dividing one large network into smaller smaller networks.
There are two types of subnetting methods available
1. FLSM: Dividing one large network into subnetworks
2. VLSM: Dividing subnetted networks into subne

Q15. What is HSRP?
HSRP, or the Hot Standby Routing Protocol, is a Cisco proprietary protocol that brings routing functionality to end devices that would otherwise not be capable of taking advantage of redundant network connections. HSRP enables a pair of Cisco routers to work together to present the appearance of a single virtual default-gateway to end devices on a LAN segment.

Q16. What types of routes are allowed into a totally stubby area?
Types of routes are:

  • OSPF intra-area routes
  • A default route

OSPF interarea and external routes are not advertised into a totally stubby area.

Q17. What are the three classes of routing protocols?
1.    Distance vector
2.    Link-state
3.    Balanced hybrid

Q18. How do distance vector routing protocols function?

Also known as Bellman-Ford-Fulkerson algorithms, distance vector routing protocols pass complete routing tables to neighboring routers. Neighboring routers then combine the received routing table with their own routing table. Each router receives a routing table from its directly connected neighbor. Distance vector routing tables include information about the total cost and the logical address of the first router on the path to each network they know about.

Q19. What is route poisoning?
With route poisoning, when a distance vector routing protocol notices that a route is no longer valid, the route is advertised with an infinite metric, signifying that the route is bad. In RIP, a metric of 16 is used to signify infinity. Route poisoning is used with holddowns.

Q20. What is the difference between an E1 and E2 OSPF route?
An E1 route contains the OSPF cost to reach the ASBR plus the cost from the ASBR to the external route. An E2 route contains only the cost from the ASBR to the external route.

Q21. What is the difference between RIP and OSPF?
RIP broadcast its routing table after each 30 seconds while OSPF only update those entries which are missing the neighbor routing table

Q22. What is the difference between Classless and Classfull routing?
Classfull routing don not advertise subnet mask information along with the network prefix while classless routing do.

Q23. What is the main purpose of areas in OSPFv2?
Routers networks are divided in to areas which are they connected to backbone area0. The areas help you to give performance and easy to handle big network

Q24. What is private vlan used for?
Private Vlan is used where hundreds of vlans are configured. You only need to make one vlan and all other vlans in this vlan.

Q25. What is route summarization?
It is a method of summarizing route in one IP/network

Q26. What is a load balancer?
Load balancer is a network device which is used to balance the load in on available nodes

Q27. What does the TTL field of an IP packet header do?
The TTL field indicates the maximum time that a packet can be on the network. Each router that processes this packet decrements the TTL value by 1. If the value reaches zero, the packet is discarded from the network. The purpose of this field is to eliminate the possibility of a packet endlessly traversing the network.

Q28. What is the primary purpose of a LAN?
The primary purpose of a local-area network is to allow resource sharing. The resources may be devices, applications, or information. Examples of shared resources are files, databases, e-mail, modems, and printers.

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