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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 an IST instance?
Trunk
Group (0-1023) priority (1-255 higher better def 100)
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.
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

2. If a wireless station needs to transmit and no other device is transmitting - what happens?
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
The station can transmit immediately and wait for an ack
Frames that barely exceed 1518B or 1622B due to headers
MAC of the end device

3. How does a LAP and a WLC authenticate between each other?
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover
By brining up a tunnel between them to carry 802.11 related messages and client data.
2
Using digital certificates

4. What is the portr ID?
16 bits (8b port priority - 8b port number)
They disguise the origin of an attack
Interim solution - uses same hardware as WEP - but uses TKIP encryption
63 kbps

5. What can cause a wireless client to switch between Aps?
RPR - RPR+ - and SSO
2 strand MMF with MT-RJ or SC connectors
A host port goes up or down
Missed beacons - dropped packets (max retry) - weak signal (data rate switches down) - an AP periodicallytries to find a stronger signal

6. Define GLBP
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
Will trunk if asked
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region
Gateway load balancing protocol - cisco proprietary

7. What are the VRRP group and priority numbers?
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves
Configure and enable DHCP snooping
Group (0-255) - priority (1-254 254 is highest - 100 default)
Switch(config-if)# vrrp xx where xx= group number

8. At what layer does EAPOL run?
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
Controls where candidate root bridges can be connected and found on a network
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.
L2

9. How does VRRP do tracking?

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10. What is the VRRP skew time?
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added
Trunk
5 (0-4 with 4 being the highest)
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL

11. What is Per VLAN STP (PVST)?
1-65535 (def 32768) lower priority - higher probability
When each AP stands alone within the larger network.
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
Yes

12. What is a drop adjacency?

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13. What happens during HSRP failover?
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
With portfast
Dynamic WEP keys that change periodically
The standby becomes active and stays active by default. Preemption can be configured

14. What is layer 3 roaming?
Only a single host connects . If one BDPU is received - it is no longer an edge port
Critical...used most often for IPT
The time that a port spends in both listening and learning states . Default 15 seconds
When a client roams between Aps in different subnets

15. How is UDLD configured?
Each network device handles packets individually with no advance reservations
Etherchannel ports have inconsistent config
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports
Isl - dot1q - negotiate (default)

16. What does uplinkfast do?
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.
Frames that barely exceed 1518B or 1622B due to headers
Promiscuous and host
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP

17. What is the STP listening state?
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
After forwarding delay - port can learn new MAC addresses
Can send and receive BDPUs
Weak key rotation

18. How does an LAP bind with a WLC?
Another router must have a higher HSRP priority and have preemt set up
Time between BDPUs sent by root bridge. Default of 2 seconds
By brining up a tunnel between them to carry 802.11 related messages and client data.
Gateway load balancing protocol - cisco proprietary

19. Define HSRP
A packet can't be switched in hardware with the FIB and must go to the L3 engine
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz
Weak key rotation

20. What does the minimum keyword do in HSRP?
0-255 (lower is better)
By an ARP access list that defines the permitted bindings
Flash (class 3)
Forces the router to wait for a period of time before attempting overthrow

21. Each switch port is a _____ ______
Collision domain
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
FIB
Hashing algorithm

22. How does a WLC hand off a client's association to another WLC?
Frames that barely exceed 1518B or 1622B due to headers
802.11
Using a mobility exchange message
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.

23. How does ISL handle COS?
Configure non-silent submode
Incoming frames dropped - but MACs learned
The total delay from start to finish
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)

24. How often are HSRP hellos sent?
3 seconds. Holdtime =3 hellos + 1
Connects with SONET or SDH
2
Real-time Transport Protocol

25. In a converged fabric - which switch(es) send config BDPUs?
When a client roams between Aps in different subnets
300 sec by default
Root
By using an Ether-IP tunnel

26. How much BW does a PSTN connection use?
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port
63 kbps
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

27. Where does layer switching occur?
Multicast to 01-80-c2-00-00-00
Between any type of interface as long as the interface can have an L3 address assigned
Weak key rotation
Using a single WAP to centralize access and control over a group of wireless devices.

28. What is an MST instance?
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN
The MST instance (MSTI) runs alongside the IST and represents an STP instance
80% of the user traffic should stay in the VLAN
Option 43

29. How should UDLD be configured?
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port
If the switch or the powered device doesn't suport power class discovery
The configureable UDLD interval must be less than max age plus two intervals of forward delay
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen

30. What does BDPU filtering do?
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
A packet can't be switched in hardware with the FIB and must go to the L3 engine
Effectively stops STP on filtered ports
Will trunk if asked

31. What does the standby HSRP router do?
If the client maintains the same IP address as it roams between Aps. All must have same VLAN - SSID - and subnet
Only the standby monitors the hello messages from the active router
2 seconds
Used when ACLs specify port ranges...used by TCAM

32. can root guard and loop guard be used together
No
From the DHCP snooping database or from static entries
Port
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

33. What is an insignificant topology change?
Cisco recommends only on the root bridge
Differentiated services code point
Can hear only BDPUs
A host port goes up or down

34. What is accelerated CEF (aCEF)?
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
Variation in delay
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port

35. How should the switch port to which a LAP be configured?
Only for trusted Cisco gear - especially phones
The campus network's backbone
Access
2 seconds (def)

36. How does HSRP plain text authentication work?
A key string of up to 8 characters is sent. Default is cisco.
Switchpotrt nonegotiate
No
Port stays up - packets from violating MACs dropped - no logging

37. How do you show HSRP status
Show standby
From the DHCP snooping database or from static entries
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client
Cisco ILP and 802.3af

38. What is a baby giant frame?
Only for the offending VLAN on the port
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.
If the client maintains the same IP address as it roams between Aps. All must have same VLAN - SSID - and subnet
Frames that barely exceed 1518B or 1622B due to headers

39. What is RTP?
Real-time Transport Protocol
Root - designated - blocking - alternate - forwarding (host)
2 seconds (def)
Use the spanning-tree root macro

40. What does port-security restrict do?
All nondesignated ports - but ok for all ports
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
By configuring every switch port to have an expected and controlled behavior
Plain text or md5

41. What does DTP do?
The wireless clients communicate directly with no other means of connectivity such as a WAP
Automatically negotiates a common trunk mode between switches
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
Auto mode

42. How can you load-balance with HSRP?
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
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
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets

43. What does VTP do?
Port with alternative path to root less desirable than root
No because they only participate if asked
Manages addition - deletion and renaming VLANs across the network
Once the CCM gives them the parameters - they use RTP

44. What are the 4 steps in DHCP negotiation?
0-255 (lower is better)
Used when ACLs specify port ranges...used by TCAM
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
Etherchannel ports have inconsistent config

45. How often are VRRP advertisements sent?
No
1 second. Backup routers can learn the interval from the master
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode
Full duplex

46. What criteria are used to size a switch block?
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
Stateful switchover - redundant sup is fully booted and init'd. Both start and run config are synched as is L2 information - and switchinterfaces.

47. How should backbonefast be configured?
Checks the source MAC in the header against the sender MAC in the ARP reply
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
An AP's coverage area
On all switches in network to enable RLQ request and reply

48. How many potential links can LACP define?
By using a hash of a key string
Group (0-255) - priority (1-254 254 is highest - 100 default)
16 - of which up to 8 are active. The others are in standby
Roughly 2000

49. What are the 6 HSRP states?
Each frame transmits its expected duration time
Sends a voltage across the receive pairs to detect a 25k ohm resistance
Disabled - init - listen - speak - standby - active
Switches make an effort to move packets as quickly as possible

50. What is a discard adjacency?
Packets are discarded due to an ACL or policy action
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.
Forces the router to wait for a period of time after the switch is reloaded before attempting to overthrow
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p