CCNP Switch Deck

Instructions:

• Answer 50 questions in 15 minutes.
• If you are not ready to take this test, you can study here.
• 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 are VACLs applied
Sends a test tone on the transmit pair. If a device is detected - CDP is used to narrow down the power class.
To a VLAN and not to a VLAN interface (SVI)
When each AP stands alone within the larger network.
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


2. What if RSTP BDPUs aren't received?
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry
Admin down
Yes
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged


3. What happens if both 802.1D and RSTP BDPUs are received?
Effectively stops STP on filtered ports
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
They disguise the origin of an attack
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another


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

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5. What does the epoch number indicate when looking at cef entries?
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
The active router. All other routers are in backup state
The number of times the CEF table has bee flushed and regenerated as a whole
1/2 and 3/6


6. What is best effort delivery QOS?
Each physical interface has a different IP address. All physical interfaces point to a virtual interface called the standby address or VIP
Incoming frames are dropped (combination of disabled - blocking - and listening)
Switches make an effort to move packets as quickly as possible
FE - GE - and aggregated FE/GE Etherchannels


7. How do VRRP routers handle preemption?
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
On by default
Data and voice over native vlan no QOS and no 802.1p trunk


8. How are errdisable triggers tuned?
Discarding - learning - forwarding
Stateful switchover - redundant sup is fully booted and init'd. Both start and run config are synched as is L2 information - and switchinterfaces.
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
Globally


9. What is a discard adjacency?
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
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Packets are discarded due to an ACL or policy action
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)


10. How does RSTP identify a topology change?
Priority (class 1)
MAC of the end device
Checks the destination MAC in the header against the target MAC in the ARP reply
Only when a nonedge port transitions to forwarding


11. At what layer does EAPOL run?
L2
Each frame transmits its expected duration time
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
Using digital certificates


12. What are the 5 STP states?
CEF is distributed completely among multiple L3 forwarding engines.
Disabled - blocking - listening - learning - forwarding
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
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


13. How does the CEF L3 engine operate?

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14. What is UDLD aggressive mode?

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15. What are the 3 RSTP port types?
2 seconds (def)
16 bits (8b port priority - 8b port number)
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
Edge - root - and point to point


16. How should backbonefast be configured?
Can hear only BDPUs
3 seconds. Holdtime =3 hellos + 1
On all switches in network to enable RLQ request and reply
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz


17. What is the range of PAgP channel group numbers?
The standby becomes active and stays active by default. Preemption can be configured
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
When each AP stands alone within the larger network.
1 to 64


18. CAM table entries are purged when....
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
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
A MAC is seen on a different port
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology


19. Where is root guard enabled?

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20. How is a WLC handoff handled when the WLCs are in different subnets?
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client
By using an Ether-IP tunnel
A MAC is seen on a different port
The ASIC


21. What are the 4 steps to extend QoS trust?
Differentiated services
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
Globally or per-port
1- enable qos - 2-define qos parameters to be trusted - 3-make trust conditional - 4-instruct IP phone how to extnd boundary


22. What is the default VTP state?
The standby becomes active and stays active by default. Preemption can be configured
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks
VTP server for domain null with no password or secure mode
They disguise the origin of an attack


23. How do you renable an err-disable port by default?
Manually
Incoming frames dropped - but MACs learned
The distribution layer should have only L3 links
L2


24. What is the IEEE standard for STP?
Root - designated - alternate - and backup
802.1D
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN


25. What is the size of a TCAM value?
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
By encapsulating each frame in a header and trailer
No
134 bits - consisting of source and destination addresses and protocol information from the packet or frame


26. What is accelerated CEF (aCEF)?
Full duplex
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
Silent
7 switches from root bridge


27. How are VACLs configured?
An ac adaptor that plugs into a wall outlet.
As a VLAN access map
Round robin - weighted - or host-dependent
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


28. What is BDPU Guard?
Configure non-silent submode
134 bits
If any BDUP is received on a port - it puts the port into the errdisable state
Distribution


29. What is the VRRP master router?
The active router. All other routers are in backup state
The master router can share the VIP
A point to point port type
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port


30. How does GLBP work?
Determines when the AVG will stop using the old VMAC in ARP replies
Collision domain
1-1005 (1 and 1002-1005 are reserved)
Routers are assigned to common GLBP group. All routers can be active and can load balance


31. What method of QOS does voice traffic use most frequently?
When a specific interface is tracked - HSRP reduces it's priority after a specified interval.
Differentiated services
Differentiated services code point
Group (0-255) - priority (1-254 254 is highest - 100 default)


32. What are the RSTP port roles?
Controls where candidate root bridges can be connected and found on a network
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
Root - designated - alternate - and backup
By encapsulating each frame in a header and trailer


33. What is the duration time in a wireless frame?
Each frame transmits its expected duration time
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
Globally
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting


34. What is an untrusted port under dhcp snooping?
Access or trunk
On by default
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds


35. What is a CEF glean?

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36. What are the RSTP port states?
12 kbps with headers and compression
Discarding - learning - forwarding
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
Per VLAN


37. What are the characteristics of the access layer?
Data and voice over native vlan no QOS and no 802.1p trunk
Data and voice over native vlan - no QOS but still uses 802.1p trunk
An L2 switch can only forward frames best effort unless going across a trunk
Low cost - high density ports - multiple scalable uplinks - vlans - traffic and protocol filtering and QoS


38. Where does VRRP send advertisements?
Multicasts to 224.0.0.18 (VRRP)
The link status stays up - but something between them has failed or is filtering traffic
10-15%
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q


39. What does the rewrite engine do?
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block
19
Another router must have a higher HSRP priority and have preemt set up


40. What does port-security protect do?
Port
Port stays up - packets from violating MACs dropped - no logging
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
Every switch and router in a network must be configured with appropriate QoS features and policies


41. What duplex setting does 802.11 use and why?
802.1D
L2
Half because transmitting and receiving stations use the same frequency
Port with best root path cost on segment


42. What is UDLD normal mode?
By default weight is 100. Can be made dynamic per interface
10-15%
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting


43. What is an IBSS?
Isl - dot1q - negotiate (default)
3 seconds. Holdtime =3 hellos + 1
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance
The wireless clients communicate directly with no other means of connectivity such as a WAP


44. What does BDPU filtering do?
Port with best root path cost on segment
1500B
Effectively stops STP on filtered ports
Trusted ports


45. How are multiple VLANs mapped to multiple SSIDs?
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
By using a trunk link
By an ARP access list that defines the permitted bindings
Value - mask - and result (VMR) combinations


46. How do IP phones communicate with each other?
Root
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports
Once the CCM gives them the parameters - they use RTP
Between interfaces that are assigned to L2 VLANs or L2 trunks


47. What is the switch block?
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting
An L2 switch can only forward frames best effort unless going across a trunk
Two distribution switches that aggregate one or more access switches
0-65535 (def 32768) lower=better


48. What does uplinkfast do?
Manually
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
Enables switches at the end of the spanning tree branches to have a functioning root port while keeping 1 or more redundant potential ports in blocking mode. When the main fails - the other comes up.
Will trunk if asked


49. what if a secondary VLAN?
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
Distribution layer


50. What is a wall wart?
It's a router that maintains routes (static or dynamic) - and populates the FIB
An ac adaptor that plugs into a wall outlet.
Only for the offending VLAN on the port
Automatically negotiates a common trunk mode between switches