CCNP Switching Interview Questions Part – 2
1.SPT Learning Port States :
The switch port listens to BPDUs and learns all the paths in the switched network. A port in learning state populates the MAC address table but doesn’t forward data frames. Forward delay means the time it takes to transition a port from listeing to learning mode,which is set to 15 seconds by default and can be seen in the show spanningp-tree output.
2.what is zip?
Zip means Zone Information Protocol. It is a session-layer protocol used by Apple-Talk to map network numbers to zone names. NBP uses ZIP in the determination of networks containing nodes that belong to a zone.
3.What is zip storm?
A broadcast storm occurring when a router running AppleTalk reproduces or transmits a route for which there is no corresponding zone name at the time of execution. The route is then forwarded by other routers downstream,thus causing a ZIP storm.
4.What is Windows Socket Interface (WinSock)?
A software interface that makes it possible for an assortment of applications to use and share an Internet connection. The WinSock software consists of a Dynamic Link Library (DLL) with supporting programs such as a dialler program that initiates the connection.
5.What are the benefits of VTP : —
VTP provides the following benefits to a switched network:
* Consistent configuration of VLANs across all switches in the network
* Allowing VLANs to be trunked over mixed networks,like Ethernet to ATM LANE or FDDI
* Accurate tracking and monitoring of VLANs
* Dynamic reporting when VLANs are added to all switches
* Plug-and-play VLAN adding to the switched network
6.What is transparent mode in Switches?
Transparent mode Switches can run in transparent mode,which means that they will only forward messages and advertisements,not add them to their own database. In version 1,the switch will check the domain name and version before forwarding,but in version 2,the switches will forward VTP messages without checking the version.
7.Explain store and forward :
Store-and-forward switching is one of three primary types of LAN switching. With the store-and-forward switching method,the LAN switch copies the entire frame onto its onboard buffers and computes the cyclic redundancy check (CRC).
Because it copies the entire frame,latency through the switch varies with frame length. The frame is discarded if it contains a CRC error,if it’s too short (less than 64 bytes including the CRC),or if it’s too long (more than 1,518 bytes including the CRC). If the frame doesn’t contain any errors,the LAN switch looks up the destination hardware address in its forwarding or switching table and determines the outgoing interface. It then forwards the frame toward its destination.
8.Briefly explain FragmentFree.
FragmentFree is a modified form of cut-through switching in which the switch waits for the collision window (64 bytes) to pass before forwarding. If a packet has an error,it almost always occurs within the first 64 bytes. FragmentFree mode provides better error checking than the cut-through mode,with practically no increase in latency.
9.The Port Aggregation Protocol (PAgP)
The Port Aggregation Protocol (PAgP) is used to add more features to the EtherChannel technology. This protocol is used to learn the capabilities of the neighbours’ EtherChannel ports. By doing this,it allows the switches to connect via Fast EtherChannel automatically. The PAgP protocol groups the ports that have the same neighbour device ID and neighbour group capability into a channel. This channel is then added to the Spanning Tree Protocol as a single bridge port.
10.What is Proxy Address Resolution Protocol (Proxy ARP)?
Proxy Address Resolution Protocol (Proxy ARP) is a variation of the ARP protocol in which an intermediate device,such as a router,sends an ARP response on behalf of an end node to the requesting host.
11.Benefits of Proxy ARP :
* No need to configure clients with a gateway
* Load balancing,although this is somewhat random
* Immediate fault tolerance for addresses not recently contacted
12.Disadvantages of Proxy ARP :
* A lot of broadcast traffic
* Must wait for ARP cache to time out in the event of failure
* No control over which router is primary and secondary
13.What are the states of Hot Standby Routing Protocol (HSRP)?
Initial,Learn,Listen,Speak,Standby and Active
14.What is the use of ICMP Router Discovery Protocol (IRDP).
This will allow hosts to use the Internet Control Message Protocol (ICMP) to find a new path when the primary router becomes unavailable.
15.Types of Distribution Trees:
Two types of trees exist in multicast: Source trees: Source trees use the architecture of the source of the multicast traffic as the root of the tree. Shared trees Shared trees use an architecture in which multiple sources share a common rendezvous point. Each of these methods is effective and allows sourced multicast data to reach an arbitrary number of recipients of the multicast group.
16.What is Data encapsulation?
Data encapsulation is the process by which the information in a protocol is wrapped,or contained,in the data section of another protocol. In the OSI reference model,each layer encapsulates the layer immediately above it as the data flows down the protocol stack.
17.What is AMI?
AMAI means Alternate Mark Inversion. it is a line-code type on T1 and E1 circuits that shows zeros as “01” during each bit cell,and ones as “11” or “00,” alternately,during each bit cell. The sending device must maintain ones density in AMI but not independently of the data stream. Also known as binarycoded,alternate mark inversion.
18.Asynchronous transmission:
Digital signals sent without precise timing,usually with different frequencies and phase relationships. Asynchronous transmissions generally enclose individual characters in control bits (called start and stop bits) that show the beginning and end of each character.
19.What is ATDM?
Asynchronous Time-Division Multiplexing: A technique for sending information,it differs from normal TDM in that the time slots are assigned when necessary rather than preassigned to certain transmitters.
20.Define Link state routing algorithm.
A routing algorithm that allows each router to broadcast or multicast information regarding the cost of reaching all its neighbours to every node in the internetwork. Link-state algorithms provide a consistent view of the network and are therefore not vulnerable to routing loops. However,this is achieved at the cost of somewhat greater difficulty in computation and more widespread traffic.