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CCNP Switch Deck

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. What is a punt adjacency?
Packets must be sent to the L3 engine for further processing
7 switches from root bridge
Arp for local subnet - if on different subnet - will arp for dgw
Discarding - learning - forwarding

2. What is an IST instance?
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
Stateful switchover - redundant sup is fully booted and init'd. Both start and run config are synched as is L2 information - and switchinterfaces.
Within a single MST region - an IST instances runs to work out a loop free topology between links where CST meets the region boundary and all switches in the region. It runs at the boundary.
Critical...used most often for IPT

3. What is a direct topology change?
One that can be detected on a switch interface (ie. Up/down)
Only for trusted Cisco gear - especially phones
Routers are assigned to common GLBP group. All routers can be active and can load balance
1 IP subnet

4. if the switchport is part of an etherchannel - Where is the network assigned
Port stays up - packets from violating MACs dropped - no logging
A group of wireless devices that share a common SSID
1500B
To the virtual port-channel interface

5. How much overlap should WAPs have?
By brining up a tunnel between them to carry 802.11 related messages and client data.
After forwarding delay - port can learn new MAC addresses
10-15%
Yes

6. What is the STP learning state?
After forwarding delay - port can learn new MAC addresses
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
On the left as you face the connector
Plain text or md5

7. what I s distributed CEF (dCEF)?
CEF is distributed completely among multiple L3 forwarding engines.
With portfast
On ports where you never expect to find a root bridge for a VLAN
The standby becomes active and stays active by default. Preemption can be configured

8. What does the src-mac option do when checking ARP replies
Value - mask - and result (VMR) combinations
Checks the source MAC in the header against the sender MAC in the ARP reply
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
Only for the offending VLAN on the port

9. What is layer 3 roaming?
Between interfaces that are assigned to L2 VLANs or L2 trunks
When a client roams between Aps in different subnets
Hashing algorithm
They should be an unconditional Etherchannel because the WLC can't negotiate a channel.

10. When are RSTP bdpus sent?
To the virtual port-channel interface
Local only
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
Globally

11. can root guard and bdpu guard be used together?
No
RPR - RPR+ - and SSO
Used to switch packets that can't be forwarded normallly due to an encapsulation failure - unresolved address - unsupported protocol - etc.
Value - mask - and result (VMR) combinations

12. What does the epoch number indicate when looking at cef entries?
Real-time Transport Protocol
Port with best root path cost on segment
No because they only participate if asked
The number of times the CEF table has bee flushed and regenerated as a whole

13. What does MSTP consist of?
Can hear only BDPUs
Regions and instances
Use sh interface on the interface and look for error counts > 10
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains

14. Where is loop guard enabled?
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information
All nondesignated ports - but ok for all ports
2 - one for control messages and one for data

15. How does packet forwarding work
Arp for local subnet - if on different subnet - will arp for dgw
Incoming frames dropped - but MACs learned
0-255
Lowest cumulative cost to root

16. What are the 6 HSRP states?
Disabled - init - listen - speak - standby - active
0-65535 (def 32768) lower=better
If a unidirectional link is detected - the switch doesn't try to reestablish the link. ULD msgs are sent once/sec for 8 seconds - then the port is err-disabled
12 kbps with headers and compression

17. Where is UDLD enabled?
All fiber-optic links between switches (must be enabled on both ends)
Low cost - high density ports - multiple scalable uplinks - vlans - traffic and protocol filtering and QoS
Virtual Router Redundancy Protocol - pretty much the same as HSRP
The time that a port spends in both listening and learning states . Default 15 seconds

18. What is the range of HSRP group numbers?
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode
0-255
An ac adaptor that plugs into a wall outlet.
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.

19. How does 802.1q handle COS?
Between interfaces that are assigned to L2 VLANs or L2 trunks
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
BGP - EIGRP - OSPF - and IS-IS.
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS

20. What are the characteristics of the core layer
An ac adaptor that plugs into a wall outlet.
Immediate (class 2)
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
When each AP stands alone within the larger network.

21. RSTP edge port
Configure the timer on the AVG and let it propagate
Feature Manager - after the ACL is created - the FM compiles the ACEs into the table
0-65535 (def 32768) lower=better
Only a single host connects . If one BDPU is received - it is no longer an edge port

22. What is the GLBP AVG?
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)
Forces the router to wait for a period of time before attempting overthrow
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
One router is the active virtual gateway - has highest priority or IP in group - answers all ARP requests and gives MAC based on load balancing

23. What is a proxy arp?

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24. What are the PAgP negotiation modes
1-LAP gets a DHCP address - 2-LAP learns IP of available WLC - 3-LAP sends a join request to WLC and receives join reply - 4-WLC sends code image - if necessary - 5-Tunnels are created
Can hear only BDPUs
Checks the destination MAC in the header against the target MAC in the ARP reply
On (all ports channel) - auto (channels when asked) - and desirable(actively asks to form a channel)

25. What does the rewrite engine do?
Show standby
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information
26-byte header - 4-byte trailer with CRC
Flash override (class 4)

26. What does the switchport host macro do?
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port
224.0.0.2 (all routers)
Cisco recommends only on the root bridge

27. How can you load-balance with HSRP?
Value - mask - and result (VMR) combinations
A group of wireless devices that share a common SSID
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
3 seconds. Holdtime =3 hellos + 1

28. Where should STP timers be configured and why?
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
On root - because the root bridge propagates timers with config BDPU
Cisco ILP and 802.3af
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure

29. How do you configure a DHCP gateway?
Needs hardware upgrade over WEP - uses AES encryption
An ac adaptor that plugs into a wall outlet.
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover

30. What are the 4 steps to extend QoS trust?
1- enable qos - 2-define qos parameters to be trusted - 3-make trust conditional - 4-instruct IP phone how to extnd boundary
On root - because the root bridge propagates timers with config BDPU
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region
If any BDUP is received on a port - it puts the port into the errdisable state

31. What is the size of ISL encapsulation?
26-byte header - 4-byte trailer with CRC
Value - mask - and result (VMR) combinations
A point to point port type
By encapsulating each frame in a header and trailer

32. How does IPT behave when the voice VLAN is in dot1p mode?
No
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac
When a port moves into forwarding or from fowarding or learning to blocking.
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p

33. How do you configure IP source guard for hosts that don't use DHCP?
After forwarding delay - port can learn new MAC addresses
By creating a static IP binding
During the time that the FIB entry is in CEF glean waiting for ARP entries - subsequent packet to that host are dropped to keep input queues from filling
Controls where candidate root bridges can be connected and found on a network

34. What are the 3 ways GLBP load-balances?
To a VLAN and not to a VLAN interface (SVI)
Round robin - weighted - or host-dependent
Disabled - init - listen - speak - standby - active
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers

35. Where shoul dmultilayer switches be implemented?
1- enable qos - 2-define qos parameters to be trusted - 3-make trust conditional - 4-instruct IP phone how to extnd boundary
Embeds the tag within the frame
Distribution layer
One router is the active virtual gateway - has highest priority or IP in group - answers all ARP requests and gives MAC based on load balancing

36. What is the traditional MLS view of switching?
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry
The port will operate under 802.1D rules. If they are received on the same port - it will run 802.1D until the migration delay expires
12 kbps with headers and compression
Route once - switch many

37. How often are CAM table entries aged?
All fiber-optic links between switches (must be enabled on both ends)
It is enabled by default on all CEF capable switches
300 sec
Normal and aggressive

38. What types of authentication does HSRP allow?
Dynamic arp inspection
Plain text or md5
Aggregation - high L3 throughput - security and policy based connectivity functions through access lists and packet filters - QoS - scalable high-speed links
With portfast

39. What is the PVLAN promiscuous mode?
Trunk
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
Will trunk if asked

40. What is an untrusted port under dhcp snooping?
Needs hardware upgrade over WEP - uses AES encryption
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
Local only
The number of times the CEF table has bee flushed and regenerated as a whole

41. If there are 2 ports with same root cost - how is the tie broken for designated port?
Each network device handles packets individually with no advance reservations
An L2 switch can only forward frames best effort unless going across a trunk
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
1-lowest root bridge ID - 2-lowest root path cost - 3-lowest bridgeID - 4-lowest port ID

42. How doed backbonefast work?
10-15%
By short-circuiting the max age timer
16 bits (8b port priority - 8b port number)
Transmits keystrokes from phone and commands from CCM

43. How should the switch port to which a WLC be configured?
Trunk
Distributed coordinion function - the use of timers to prevent wireless collisions
Up to 4 can be used in a group. Called active virtual forwarders (AVF)
A key string of up to 8 characters is sent. Default is cisco.

44. What are 2 ways to configure VLAN and VTP information?
Needs hardware upgrade over WEP - uses AES encryption
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy
1-LAP gets a DHCP address - 2-LAP learns IP of available WLC - 3-LAP sends a join request to WLC and receives join reply - 4-WLC sends code image - if necessary - 5-Tunnels are created
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN

45. can root guard and loop guard be used together
1/2 and 3/6
All nondesignated ports - but ok for all ports
A host port goes up or down
No

46. WPA encryption
The number of times the entry has been updated since the table was generated
Can send and receive BDPUs
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
Interim solution - uses same hardware as WEP - but uses TKIP encryption

47. Define GLBP
1-65535 (def 32768) lower priority - higher probability
Gateway load balancing protocol - cisco proprietary
Untrusted
Promiscuous and host

48. What is RPR+?

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49. What is a wireless mobility group?
0-255
A client can roam to any WLC as long as it stays in a mobility group
By encapsulating each frame in a header and trailer
The number of times the entry has been updated since the table was generated

50. What is the default mode of load balancing?
Src-dst-ip
1-LAP gets a DHCP address - 2-LAP learns IP of available WLC - 3-LAP sends a join request to WLC and receives join reply - 4-WLC sends code image - if necessary - 5-Tunnels are created
Immediate (class 2)
Round robin - weighted - or host-dependent