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. can root guard and bdpu guard be used together?
1-(opt) set system priority - 2-select interface(s) - 3-assign the protocol - 4-set the mode - 5-(opt) set the port priority
No
Used when there are 1 or more VLANs mapped to a single STP instance
If any BDUP is received on a port - it puts the port into the errdisable state


2. What happens when an ARP reply is received on an untrusted port?

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3. What is the STP forward delay timer?
The station can transmit immediately and wait for an ack
The time that a port spends in both listening and learning states . Default 15 seconds
No
The standby becomes active and stays active by default. Preemption can be configured


4. What are the 5 STP states?
With the skinny protocol
Group (0-255) - priority (1-254 254 is highest - 100 default)
Disabled - blocking - listening - learning - forwarding
Discarding - learning - forwarding


5. where does L2 switching occur?
26-byte header - 4-byte trailer with CRC
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
Between interfaces that are assigned to L2 VLANs or L2 trunks
Another router must have a higher HSRP priority and have preemt set up


6. What is unique about HSRP group numbers?
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root
RPR - RPR+ - and SSO
Switch(config-if)# glbp xx where xx = group number
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another


7. How does a WLC hand off a client's association to another WLC?
Using a mobility exchange message
Can send and receive BDPUs
1-enable AAA on switch - 2-define RADIUS servers - 3-define authentication method - 4-enable 802.1x on switch - 5-conf. 802.1x ports - 6-allow hosts
Per VLAN


8. What is the standard for WLANs?
Aggregation - high L3 throughput - security and policy based connectivity functions through access lists and packet filters - QoS - scalable high-speed links
1- inferior BDPU on blocked-considered alternative - 2-inferior on root-all blocked ports considered alternate - 3-if inferior arrives on root and no blocked ports - assumes loss of connectivity to root
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
802.11


9. What pins does FE use?
1/2 and 3/6
Between any type of interface as long as the interface can have an L3 address assigned
1- root bridge is elected - 2-the state of eery switch port in the STP domain must be brought from blocking state to the appropriate state
Switch(config-if)# glbp xx where xx = group number


10. How should UDLD be configured?
Trusted or untrusted
The configureable UDLD interval must be less than max age plus two intervals of forward delay
Collision domain
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config


11. What is DSCP codepoint AF31(26)?
Port is forced to never authorize any connected client
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
Flash (class 3)
Will trunk if asked


12. What is the DIFS?
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
Access or trunk
The DCF interframe space- the random backoff time before a wireless set can transmit
Best effort delivery - integrated services model - and differentiated services model


13. How do IP phones communicate with each other?
MAC addresses are learned from the source MAC of incoming frames. If the destination address is unknown - the frame is flooded out all except the receiving port.
By default weight is 100. Can be made dynamic per interface
Once the CCM gives them the parameters - they use RTP
L2


14. How is an instance defined?
By name - config revision - and instance to vlan mapping table
63 kbps
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
80% of the user traffic should stay in the VLAN


15. Where shoul dmultilayer switches be implemented?
Distribution layer
Access or trunk
CEF is distributed completely among multiple L3 forwarding engines.
Port stays up - packets from violating MACs dropped - no logging


16. How does a DAI enabled switch gather trusted ARP info?
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
From the DHCP snooping database or from static entries
Sends a voltage across the receive pairs to detect a 25k ohm resistance


17. What is the VRRP skew time?
Based on priority (0-255). Default is 100. Highest IP is tie breaker
Port stays up - packets from violating MACs dropped - no logging
Switching Database Manager - configures and prunes TCAM partitions
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added


18. What does UDLD do?
On the left as you face the connector
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
1-(opt) set system priority - 2-select interface(s) - 3-assign the protocol - 4-set the mode - 5-(opt) set the port priority


19. What are the 3 RSTP port types?
No
Edge - root - and point to point
Port with best root path cost
Half because transmitting and receiving stations use the same frequency


20. How is an RSTP edge port configured
16 - of which up to 8 are active. The others are in standby
With portfast
Route processor redundancy - redundant sup is partially booted and initialized and must reload module in the switch and init all sup functions
By sending a gratuitous ARP


21. How does the CEF L3 engine operate?

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22. What ILP mode are all ports in by default?
Completed dhcp bindings - mac addresses - IP addresses - etc.
Auto mode
Makes use of the DHCP snooping database and static ip source binding entries. If enabled - switch will test addresses
The master router can share the VIP


23. WPA encryption
Interim solution - uses same hardware as WEP - but uses TKIP encryption
On (all ports channel) - auto (channels when asked) - and desirable(actively asks to form a channel)
Cisco ILP and 802.3af
The station can transmit immediately and wait for an ack


24. At what layer does EAPOL run?
Port with best root path cost on segment
L2
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.
The campus network's backbone


25. What is the STP learning state?
Should be used on access switches - can't be used on root - keeps enabled switch from becoming root by raising priority of switch and all ports - making them undesirable
After forwarding delay - port can learn new MAC addresses
Up to 4 can be used in a group. Called active virtual forwarders (AVF)
Missed beacons - dropped packets (max retry) - weak signal (data rate switches down) - an AP periodicallytries to find a stronger signal


26. What is errdisable pagp-flap?
Forces the router to wait for a period of time after the switch is reloaded before attempting to overthrow
Etherchannel ports have inconsistent config
134 bits - consisting of source and destination addresses and protocol information from the packet or frame
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)


27. What is route caching?

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28. How do you configure IP source guard for hosts that don't use DHCP?
Configure the timer on the AVG and let it propagate
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
By creating a static IP binding


29. Where are security and QoS ACLs stored?
TCAM
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string
When the size of a cell is intentionally reduced
Prevents the dhcp binding DB from being checked.


30. How is DHCP snooping enabled (scope)?
Globally
To a VLAN and not to a VLAN interface (SVI)
Best effort delivery - integrated services model - and differentiated services model
Should be used on access switches - can't be used on root - keeps enabled switch from becoming root by raising priority of switch and all ports - making them undesirable


31. What feedback mechanism does wireless use?
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
0-255 (lower is better)
A packet can't be switched in hardware with the FIB and must go to the L3 engine
When a wireless station transmits a frame - the receiving one must send an ack


32. How does packet forwarding work
Arp for local subnet - if on different subnet - will arp for dgw
Use the spanning-tree root macro
It can't
Half-duplex


33. What is the size of ISL encapsulation?
By encapsulating each frame in a header and trailer
The MST instance (MSTI) runs alongside the IST and represents an STP instance
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
26-byte header - 4-byte trailer with CRC


34. How are BDPUs spread?
BGP - EIGRP - OSPF - and IS-IS.
Show standby
Multicast to 01-80-c2-00-00-00
By encapsulating each frame in a header and trailer


35. What is a proxy arp?

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36. What is a community secondary VLAN?
Hosts within a secondary can communicate with each other and with the primary - but not with another secondary vlan
1-lowest root bridge ID - 2-lowest root path cost - 3-lowest bridgeID - 4-lowest port ID
They disguise the origin of an attack
BGP - EIGRP - OSPF - and IS-IS.


37. What is UDLD normal mode?
Virtual Router Redundancy Protocol - pretty much the same as HSRP
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
With portfast
Regions and instances


38. How should the switch port to which an autonomous AP be configured?
Sends a test tone on the transmit pair. If a device is detected - CDP is used to narrow down the power class.
Trunk
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
26-byte header - 4-byte trailer with CRC


39. What does the rewrite engine do?
Priority (class 1)
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information


40. If a wireless station needs to transmit and another device is transmitting - what happens?
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz
224.0.0.2 (all routers)
On ports where you never expect to find a root bridge for a VLAN
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting


41. What must you be sure of if AP cells overlap?

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42. How do you show HSRP status
Show standby
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
7 switches from root bridge
Src-dst-ip


43. What is 802.1x auto?
A client can roam to any WLC as long as it stays in a mobility group
Globally
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client
Between interfaces that are assigned to L2 VLANs or L2 trunks


44. What does MSTP do?
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves
Used when there are 1 or more VLANs mapped to a single STP instance
Edge - root - and point to point
1-1005 (1 and 1002-1005 are reserved)


45. static vlans offer ____ based membership
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge
Port stays up - packets from violating MACs dropped - no logging
Configure non-silent submode
Port


46. Which 4 things must be agreeable to trunk?
Globally
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN
134 bits


47. What is backbonefast?
Normal and aggressive
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client


48. What is topology-basec caching?
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
The standby becomes active and stays active by default. Preemption can be configured
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
Flash override (class 4)


49. RSTP uses which standard?
Either desirable or auto mode
Controls where candidate root bridges can be connected and found on a network
802.1w
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port


50. if the switchport is part of an etherchannel - Where is the network assigned
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
To the virtual port-channel interface
The link status stays up - but something between them has failed or is filtering traffic
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