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CCNP Switch Deck

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Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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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 2 tunnelling mechanisms do the LAP and WLC use to communicate?
LWAPP (Cisco proprietary) and CAP-WAP (standards based)
Data and voice over native vlan - no QOS but still uses 802.1p trunk
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings

2. What does the SP do?
Used when there are 1 or more VLANs mapped to a single STP instance
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
Use the spanning-tree root macro
Immediate (class 2)

3. By default - what submode does PAgP operate in with the desirable and auto modes?
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
Route processor redundancy - redundant sup is partially booted and initialized and must reload module in the switch and init all sup functions
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz
Silent

4. How far chould a VLAN extend?
Prevents the dhcp binding DB from being checked.
Turn on port security
It is enabled by default on all CEF capable switches
Distribution layer

5. How do you configure IP source guard for hosts that don't use DHCP?
They should be an unconditional Etherchannel because the WLC can't negotiate a channel.
Only a single host connects . If one BDPU is received - it is no longer an edge port
1 per segment
By creating a static IP binding

6. What are the RSTP port states?
By using a hash of a key string
Discarding - learning - forwarding
The total delay from start to finish
26-byte header - 4-byte trailer with CRC

7. At what layer does EAPOL run?
Configuration and TCN
Switches make an effort to move packets as quickly as possible
L2
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based

8. How are BDPUs spread?
Used when there are 1 or more VLANs mapped to a single STP instance
Multicast to 01-80-c2-00-00-00
Differentiated services code point
Receives the first packet of a traffic flow and routes it

9. What is the acceptible range of VLANS?
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
A group of wireless devices that share a common SSID
1-1005 (1 and 1002-1005 are reserved)
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p

10. unknown unicast flooding
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.
Either desirable or auto mode
L2
Distribution

11. What is an MST instance?
The MST instance (MSTI) runs alongside the IST and represents an STP instance
Trusted ports
To the virtual port-channel interface
If the switch or the powered device doesn't suport power class discovery

12. What is an ESS?
7 switches from root bridge
The active router. All other routers are in backup state
When the AP uplinks to an Ethernet network.
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information

13. How many links can be used in an EtherChannel?
Switchpotrt nonegotiate
The MST instance (MSTI) runs alongside the IST and represents an STP instance
0007.b4xx.xxyy where xx.xx is six 0 bits followed by a 10-bit GLBP group numberr. Yyyy is the virtual forwarder number
2-8 FE - GE - or 10GE are bundled.

14. How does DSCP handle IP precedence?
Packets must be sent to the L3 engine for further processing
5 classes with 3 drop precedences
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode

15. 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
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance
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
802.1D

16. What is NSF?
All user ports that have portfast enabled
If any BDUP is received on a port - it puts the port into the errdisable state
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover

17. What is the port number range?
0-255
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge
Connects with SONET or SDH
Almost eliminates listening and learning states for single hosts on an access link

18. What is a wall wart?
63 kbps
An ac adaptor that plugs into a wall outlet.
80% of the user traffic should stay in the VLAN
Will trunk if asked

19. RSTP forwarding state
By brining up a tunnel between them to carry 802.11 related messages and client data.
Manually
Frames are forwarded
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding

20. What does the epoch number indicate when looking at cef entries?
Multicasts to 224.0.0.18 (VRRP)
The number of times the CEF table has bee flushed and regenerated as a whole
It's a router that maintains routes (static or dynamic) - and populates the FIB
The MST instance (MSTI) runs alongside the IST and represents an STP instance

21. Can two switches in the auto(PAgP) or passive (LACP) mode create a channel? Why?
No because they only participate if asked
Each frame transmits its expected duration time
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
80% of the user traffic should stay in the VLAN

22. can root guard and bdpu guard be used together?
On all switches in network to enable RLQ request and reply
Best effort delivery - integrated services model - and differentiated services model
No
Only when a nonedge port transitions to forwarding

23. What does Root Guard do?
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.
Controls where candidate root bridges can be connected and found on a network
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
0-255

24. What are the caveats for HSRP port tracking?
1-65535 (def 32768) lower priority - higher probability
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
Another router must have a higher HSRP priority and have preemt set up
Frames that barely exceed 1518B or 1622B due to headers

25. How is Root Guard used?
Those that connect to other switches
On ports where you never expect to find a root bridge for a VLAN
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
Isolated and community

26. What is an insignificant topology change?
Globally
Packets are discarded due to an ACL or policy action
A host port goes up or down
Completed dhcp bindings - mac addresses - IP addresses - etc.

27. 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
Only when a nonedge port transitions to forwarding
The same as a standby group in HSRP
Trunk

28. How does 802.3af do power discovery?
The station can transmit immediately and wait for an ack
Sends a voltage across the receive pairs to detect a 25k ohm resistance
3 seconds. Holdtime =3 hellos + 1
Dynamic WEP keys that change periodically

29. How often are VRRP advertisements sent?
Differentiated services
1 second. Backup routers can learn the interval from the master
Flash override (class 4)
As a VLAN access map

30. What can cause a wireless client to switch between Aps?
Missed beacons - dropped packets (max retry) - weak signal (data rate switches down) - an AP periodicallytries to find a stronger signal
A group of wireless devices that share a common SSID
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
134 bits - consisting of source and destination addresses and protocol information from the packet or frame

31. How are GLBP timers used?
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
Normal and aggressive
The active router. All other routers are in backup state

32. How does IPT behave when the voice VLAN is in vlan-id mode?
The MST instance (MSTI) runs alongside the IST and represents an STP instance
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
The master router can share the VIP
Port

33. What is a BSS?
Using a single WAP to centralize access and control over a group of wireless devices.
Yes
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS

34. What are the gotchas for uplinkfast?

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35. What is the SDM?
26-byte header - 4-byte trailer with CRC
Incoming frames dropped - but MACs learned
Switching Database Manager - configures and prunes TCAM partitions
RADIUS

36. What are the steps to configuring HSRP MD5 authentication?
Isl - dot1q - negotiate (default)
5 classes with 3 drop precedences
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string
Collision domain

37. What is dynamic desireable?
2 seconds
The port asks the other end to trunk
Priority (class 1)
Only for the offending VLAN on the port

38. How does a LAP and a WLC authenticate between each other?
1-1005 (1 and 1002-1005 are reserved)
Using digital certificates
Packets must be sent to the L3 engine for further processing
Best effort delivery - integrated services model - and differentiated services model

39. How does every HSRP config command begin?
By brining up a tunnel between them to carry 802.11 related messages and client data.
By short-circuiting the max age timer
They should be an unconditional Etherchannel because the WLC can't negotiate a channel.
Switch(config-if)# standby xx where x= group number

40. What is Per VLAN STP (PVST)?
The same as a standby group in HSRP
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
Trunk

41. What categories can ports be in with dhcp snooping enabled?
FE and GE
Trusted or untrusted
Dynamic WEP keys that change periodically
Regions and instances

42. What does DTP do?
1 IP subnet
Automatically negotiates a common trunk mode between switches
By name - config revision - and instance to vlan mapping table
The standby becomes active and stays active by default. Preemption can be configured

43. What types of authentication does HSRP allow?
Both layer 2 switching and IVR
1 to 64
Access
Plain text or md5

44. How often are CAM table entries aged?
Differentiated services code point
300 sec
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based
Root

45. How is DHCP snooping enabled (scope)?
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance
All user ports that have portfast enabled
Globally

46. What is the default mode of load balancing?
If the switch or the powered device doesn't suport power class discovery
Src-dst-ip
Option 43
Full duplex

47. RSTP BPDU structure
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
An AP's coverage area
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
Used when ACLs specify port ranges...used by TCAM

48. How do Cisco IP phones communicate with the CCM?
LACP port priority
MAC of the end device
With the skinny protocol
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

49. When looking at the sh spanning tree output - What does P2P denote?
0-255
Group (0-255) - priority (1-254 254 is highest - 100 default)
All L2 connectivity should be contained within the access layer.
A point to point port type

50. What is integrated services model QOS?
Root - designated - alternate - and backup
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
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.
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