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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. How does 802.1q handle COS?
A client can roam to any WLC as long as it stays in a mobility group
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
Transmits keystrokes from phone and commands from CCM

2. What criteria are used to size a switch block?
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
Globally
Incoming frames are dropped (combination of disabled - blocking - and listening)
Configure the timer on the AVG and let it propagate

3. What is an untrusted port under dhcp snooping?
0-255
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
Half because transmitting and receiving stations use the same frequency
Via an 802.1Q trunk or a single VLAN access port

4. What is errdisable pagp-flap?
A TCN BDPU is sent out of the switch's root port. The switch will continue sending TCN's every hello interval until ack'd by upstream neighbor. The root bridge will send a Config BDPU to all switches
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies
Etherchannel ports have inconsistent config
Can send and receive BDPUs

5. How much BW does a PSTN connection use?
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN
The time that a port spends in both listening and learning states . Default 15 seconds
63 kbps
When the AP uplinks to an Ethernet network.

6. What is the PVLAN promiscuous mode?
1 IP subnet
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
Switching Database Manager - configures and prunes TCAM partitions
RPR - RPR+ - and SSO

7. what if a secondary VLAN?
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
LWAPP (Cisco proprietary) and CAP-WAP (standards based)
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN
An instance of RSTP running for each VLAN on the switch. Changing from PVST to RPVST+ is disruptive

8. what I s distributed CEF (dCEF)?
Yes
Switches make an effort to move packets as quickly as possible
Dynamic WEP keys that change periodically
CEF is distributed completely among multiple L3 forwarding engines.

9. How does ISL do trunking?
All L2 connectivity should be contained within the access layer.
Priority (class 1)
By encapsulating each frame in a header and trailer
Best effort delivery - integrated services model - and differentiated services model

10. What data does DHCP snooping track?
Completed dhcp bindings - mac addresses - IP addresses - etc.
Priority (class 1)
FE and GE
224.0.0.2 (all routers)

11. How does adding option-82 to DHCP snooping affect things?

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12. How does every HSRP config command begin?
A group of wireless devices that share a common SSID
Switch(config-if)# standby xx where x= group number
2 seconds (def)
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs

13. What are the gotchas for uplinkfast?

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14. RSTP learning state
Incoming frames dropped - but MACs learned
The ASIC
Trunk
Half-duplex

15. What are the restrictions for bundling into an Etherchannel?
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block
Completed dhcp bindings - mac addresses - IP addresses - etc.
Effectively stops STP on filtered ports
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings

16. What is an IST instance?
Switch(config-if)# glbp xx where xx = group number
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.
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.

17. How are RSTP point to point ports determined?
Promiscuous and host
Routers are assigned to common GLBP group. All routers can be active and can load balance
Automatically by duplex mode in use. Full duplex are point ot point. Half duplex ports use traditional 802.1D convergence is used.
By sending a gratuitous ARP

18. What are the 5 STP states?
On root - because the root bridge propagates timers with config BDPU
When the size of a cell is intentionally reduced
Disabled - blocking - listening - learning - forwarding
Dynamic arp inspection

19. How often are CAM table entries aged?
To the virtual port-channel interface
300 sec by default
300 sec
Both layer 2 switching and IVR

20. What is a proxy arp?

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21. Where is bdpu guard enabled?
Each frame transmits its expected duration time
By name - config revision - and instance to vlan mapping table
All user ports that have portfast enabled
A key string of up to 8 characters is sent. Default is cisco.

22. What does the SP do?
Value - mask - and result (VMR) combinations
Automatically negotiates a common trunk mode between switches
Listens to the first packet going to router and away from the router. If it can switch in both directions - it learns a shortcut path so subsequent packets can be switched without the RP
10-15%

23. If a wireless station needs to transmit and no other device is transmitting - what happens?
63 kbps
From the DHCP snooping database or from static entries
By using a hash of a key string
The station can transmit immediately and wait for an ack

24. Where should STP timers be configured and why?
802.1x with EAP over LAN (EAPOL)
Regions and instances
On root - because the root bridge propagates timers with config BDPU
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

25. What is latency?
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
The port asks the other end to trunk
The total delay from start to finish
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks

26. What is a wireless mobility group?
Set the native VLAN of a trunk to a bogus or unused VLAN ID then prune the native VLAN off both ends of the trunk
By an ARP access list that defines the permitted bindings
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz
A client can roam to any WLC as long as it stays in a mobility group

27. What is layer 2 roaming?
If the client maintains the same IP address as it roams between Aps. All must have same VLAN - SSID - and subnet
Switching Database Manager - configures and prunes TCAM partitions
The ASIC
Use sh interface on the interface and look for error counts > 10

28. What is the GLBP AVG?
Only the standby monitors the hello messages from the active router
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
802.1w
Silent

29. What is an SVI?
VTP server for domain null with no password or secure mode
Switched Virtual Interface - an L3 address can be assigned to a logical interface that represents an entire VLAN - which becomes the DGW for that VLAN
1 per segment
Used when there are 1 or more VLANs mapped to a single STP instance

30. What are the 3 redundant supervisor modes?
One that can be detected on a switch interface (ie. Up/down)
With the skinny protocol
Needs hardware upgrade over WEP - uses AES encryption
RPR - RPR+ - and SSO

31. What is a root link query (RLQ)?
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
A client can roam to any WLC as long as it stays in a mobility group
Isolated and community
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge

32. How far chould a VLAN extend?
Distribution layer
Because each frame is checked
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
Only the standby monitors the hello messages from the active router

33. What do you need to determine to use MSTP?
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
The time that a port spends in both listening and learning states . Default 15 seconds
Arp for local subnet - if on different subnet - will arp for dgw
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance

34. What happens when the topology changes?

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35. RSTP point to point port
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
The L3 forwarding engine can't forward the packet in hardware because there is no L2 next-hop address - so the packet is sent to the L3 engine to generate the ARP response
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
Port that connects to another switch and becomes a designated port

36. For QoS - switch uplinks should always be considered as ____ _____?
0-255 (lower is better)
Trusted ports
The same as a standby group in HSRP
No shut

37. How does every VRRP command begin?
By using a hash of a key string
Used when there are 1 or more VLANs mapped to a single STP instance
Normal and aggressive
Switch(config-if)# vrrp xx where xx= group number

38. How do you configure DAI for statically configured IP addresses?
Any ports associated with an isolated vlan can reach the primary - but not any other secondary. Hosts withn an isolated vlan can't reach each other
By an ARP access list that defines the permitted bindings
Disabled - blocking - listening - learning - forwarding
1 per segment

39. static vlans offer ____ based membership
A port can only forward or relay BDPUs - but can't receive them - disabled by default - enabled per-port - blocks port when superior BDPUs are received
A client can roam to any WLC as long as it stays in a mobility group
Another router must have a higher HSRP priority and have preemt set up
Port

40. What is the access layer best practice?
Packets must be sent to the L3 engine for further processing
All L2 connectivity should be contained within the access layer.
Edge - root - and point to point
Disabled - init - listen - speak - standby - active

41. Where is the QoS trust boundary usually configured on an IP phone?
Trunk
Usually QoS from VOIP but not PC dataa
On ports where you never expect to find a root bridge for a VLAN
Those that connect to other switches

42. What is the STP forward delay timer?
Real-time Transport Protocol
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
The time that a port spends in both listening and learning states . Default 15 seconds
Each network device handles packets individually with no advance reservations

43. How does DSCP handle IP precedence?
Missed beacons - dropped packets (max retry) - weak signal (data rate switches down) - an AP periodicallytries to find a stronger signal
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
Differentiated services
5 classes with 3 drop precedences

44. How is DHCP snooping enabled (scope)?
Either desirable or auto mode
Port stays up - packets from violating MACs dropped - no logging
VTP server for domain null with no password or secure mode
Globally

45. What is the bridge priority range?
Forces the router to wait for a period of time before attempting overthrow
Any ports associated with an isolated vlan can reach the primary - but not any other secondary. Hosts withn an isolated vlan can't reach each other
0-65535 (def 32768) lower=better
Routers are assigned to common GLBP group. All routers can be active and can load balance

46. What is the STP hello timer?
Gateway load balancing protocol - cisco proprietary
Time between BDPUs sent by root bridge. Default of 2 seconds
No
Sends a test tone on the transmit pair. If a device is detected - CDP is used to narrow down the power class.

47. What is the GLBP redirect timer?
1 to 64
No
Globally
Determines when the AVG will stop using the old VMAC in ARP replies

48. When looking at the sh spanning tree output - What does P2P peer(STP) denote?
By an ARP access list that defines the permitted bindings
0-255
A point to point port type but the neighboring device runs traditional 802.1D STP
Limits the number if dhcp requests on a port

49. What is an ESS?
1/2 and 3/6
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
When the AP uplinks to an Ethernet network.
A VLAN that spans the entire fabric

50. What is step 1 of enabling IP source guard?
To a VLAN and not to a VLAN interface (SVI)
One that can be detected on a switch interface (ie. Up/down)
Configure and enable DHCP snooping
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root