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. What are the gotchas for uplinkfast?

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

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3. What is a service set?
Switchpotrt nonegotiate
Port with alternative path to root less desirable than root
The link status stays up - but something between them has failed or is filtering traffic
A group of wireless devices that share a common SSID


4. What is the GLBP redirect timer?
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
By short-circuiting the max age timer
Yes
Determines when the AVG will stop using the old VMAC in ARP replies


5. What is the port number range?
0-255
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
Edge - root - and point to point
A VLAN that spans the entire fabric


6. What does IP source guard do?
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
Real-time Transport Protocol
Makes use of the DHCP snooping database and static ip source binding entries. If enabled - switch will test addresses


7. What is a CEF glean?

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8. What does BDPU filtering do?
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
802.1D
Effectively stops STP on filtered ports
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


9. How do IP phones communicate with each other?
Once the CCM gives them the parameters - they use RTP
Needs hardware upgrade over WEP - uses AES encryption
134 bits
The campus network's backbone


10. How does every GLBP command begin
Edge - root - and point to point
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
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information
Switch(config-if)# glbp xx where xx = group number


11. One vlan should =
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
Etherchannel ports have inconsistent config
1 IP subnet
1 per segment


12. How are BDPUs spread?
Multicast to 01-80-c2-00-00-00
2 - one for control messages and one for data
Yes
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based


13. What is a LACP priority?
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)
On ports where you never expect to find a root bridge for a VLAN
Distribution layer


14. RSTP backup port
On by default
No
Port with redundant - but less deisrable connection to a segment. Possibly root candidate
The link status stays up - but something between them has failed or is filtering traffic


15. What is DSCP codepoint AF21(18)?
On the left as you face the connector
Using digital certificates
To a VLAN and not to a VLAN interface (SVI)
Immediate (class 2)


16. What is the default network diameter?
7 switches from root bridge
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
Distributed coordinion function - the use of timers to prevent wireless collisions
Gateway load balancing protocol - cisco proprietary


17. What is the VRRP master router?
The active router. All other routers are in backup state
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
Port
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client


18. How do you show HSRP status
Show standby
No shut
Each frame transmits its expected duration time
Configure the timer on the AVG and let it propagate


19. What is UDLD normal mode?
1 second. Backup routers can learn the interval from the master
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
No because they only participate if asked
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated


20. How does IPT behave when the voice VLAN is in untagged mode?
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server
Sends a voltage across the receive pairs to detect a 25k ohm resistance
Data and voice over native vlan - no QOS but still uses 802.1p trunk
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based


21. How is DHCP snooping enabled (scope)?
1-(opt) set system priority - 2-select interface(s) - 3-assign the protocol - 4-set the mode - 5-(opt) set the port priority
The active router. All other routers are in backup state
Globally
Root - designated - alternate - and backup


22. What can the Etherchannel hash use?
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
Collision domain


23. How many virtual MACs can GLBP have?
By configuring every switch port to have an expected and controlled behavior
Sends a test tone on the transmit pair. If a device is detected - CDP is used to narrow down the power class.
Up to 4 can be used in a group. Called active virtual forwarders (AVF)
To the virtual port-channel interface


24. RSTP point to point port
BGP - EIGRP - OSPF - and IS-IS.
Only the standby monitors the hello messages from the active router
Port that connects to another switch and becomes a designated port
From the DHCP snooping database or from static entries


25. What is errdisable pagp-flap?
Hashing algorithm
Yes to both
Etherchannel ports have inconsistent config
The redundant SUP is booted and sup and route engine is init'd. No L2 or L3 functions are started. Allows switchports to retain state


26. What is DSCP?
Differentiated services code point
Packets must be sent to the L3 engine for further processing
Each physical interface has a different IP address. All physical interfaces point to a virtual interface called the standby address or VIP
When a wireless station transmits a frame - the receiving one must send an ack


27. What are the 5 STP port roles?
On all switches in network to enable RLQ request and reply
Control functions
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings
Root - designated - blocking - alternate - forwarding (host)


28. If a wireless station needs to transmit and another device is transmitting - what happens?
Determines when the AVG will stop using the old VMAC in ARP replies
Discarding - learning - forwarding
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting
Yes


29. What is the STP forwarding state?
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root


30. What are the 2 types of secondary VLAN?
FE and GE
Isolated and community
224.0.0.2 (all routers)
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge


31. What is the VRRP skew time?
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
Compatible with 802.11b - up to 54Mbps in 12 data rates - 3 channels - 2.4Ghz


32. How should backbonefast be configured?
7 switches from root bridge
Group (0-255) - priority (1-254 254 is highest - 100 default)
On all switches in network to enable RLQ request and reply
By using a trunk link


33. What is the RSTP default hello interval?
It can't
5 (0-4 with 4 being the highest)
2 seconds
No


34. What happens during HSRP failover?
A host port goes up or down
Both ends should be on because on modes doesn't send PAgP or LACP packets
Prevents the dhcp binding DB from being checked.
The standby becomes active and stays active by default. Preemption can be configured


35. How does 802.3af do power discovery?
Port with redundant - but less deisrable connection to a segment. Possibly root candidate
Sends a voltage across the receive pairs to detect a 25k ohm resistance
Critical...used most often for IPT
Half-duplex


36. What does Root Guard do?
Lowest cumulative cost to root
Controls where candidate root bridges can be connected and found on a network
If any BDUP is received on a port - it puts the port into the errdisable state
No because they only participate if asked


37. What is the LACP priority range?
1-65535 (def 32768) lower priority - higher probability
By short-circuiting the max age timer
2-8 FE - GE - or 10GE are bundled.
26-byte header - 4-byte trailer with CRC


38. What is the bridge priority range?
Switches make an effort to move packets as quickly as possible
Port
0-65535 (def 32768) lower=better
2-8 FE - GE - or 10GE are bundled.


39. Where is root guard enabled?

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40. RSTP BPDU structure
5 (0-4 with 4 being the highest)
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
By creating a static IP binding
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan


41. What is the cost of a 1Gbps link?
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
On (all ports channel) - auto (channels when asked) - and desirable(actively asks to form a channel)
4
It is enabled by default on all CEF capable switches


42. How does RSTP converge?
Use sh interface on the interface and look for error counts > 10
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
Promiscuous and host
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves


43. What are the steps of RSTP convergence?
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
802.11
Flash (class 3)
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable


44. How does VRRP do tracking?

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45. Which fiber is the receive?
Globally
On the left as you face the connector
1-ID link path costs - 2-ID roodt bridge - 3-select root port (1/switch) - 4-select designated port (1/segment) - 5-ID blocking port
Reboots and searches for a new WLC


46. What is a cell?

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47. How do you renable an err-disable port by default?
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
Between any type of interface as long as the interface can have an L3 address assigned
Manually
Root - designated - blocking - alternate - forwarding (host)


48. What is an insignificant topology change?
On (all ports channel) - auto (channels when asked) - and desirable(actively asks to form a channel)
Needs hardware upgrade over WEP - uses AES encryption
A host port goes up or down
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


49. How does ISL do trunking?
No because they only participate if asked
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
By encapsulating each frame in a header and trailer
Value - mask - and result (VMR) combinations


50. What is the access layer best practice?
Trusted ports
No
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
All L2 connectivity should be contained within the access layer.