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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.
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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 is the range of HSRP group numbers?
0-255
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
Globally or per-port
Half because transmitting and receiving stations use the same frequency

2. What does UDLD do?
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
Switchpotrt nonegotiate
16 bits (8b port priority - 8b port number)
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)

3. What is dhcp snooping rate limiting?
No
Manually
Forces the router to wait for a period of time before attempting overthrow
Limits the number if dhcp requests on a port

4. Which 4 things must be agreeable to trunk?
0-255
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Trunk
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN

5. What happens during HSRP failover?
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
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
After forwarding delay - port can learn new MAC addresses

6. What is the default FE duplex?
Full duplex
16 - of which up to 8 are active. The others are in standby
If any BDUP is received on a port - it puts the port into the errdisable state
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN

7. What is a CEF punt?

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8. How do you prevent switch spoofing?
During the time that the FIB entry is in CEF glean waiting for ARP entries - subsequent packet to that host are dropped to keep input queues from filling
By configuring every switch port to have an expected and controlled behavior
Usually QoS from VOIP but not PC dataa
Configuration and TCN

9. How does DSCP handle IP precedence?
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
No
5 classes with 3 drop precedences
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region

10. can root guard and udld be used together?
Feature Manager - after the ACL is created - the FM compiles the ACEs into the table
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
To the virtual port-channel interface
Yes

11. How does IPT behave when the voice VLAN is in vlan-id mode?
Automatically using DTP and CDP
300 sec
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
Priority (class 1)

12. When a host is connected to a switchport - why aren't frame errors propagated?
Matching SSID - compatible data rate - authentication credentials
By short-circuiting the max age timer
Because each frame is checked
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen

13. What is the acceptible range of VLANS?
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
1-1005 (1 and 1002-1005 are reserved)
Checks the destination MAC in the header against the target MAC in the ARP reply
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.

14. What is an ESS?
Use sh interface on the interface and look for error counts > 10
Configuration and TCN
Critical...used most often for IPT
When the AP uplinks to an Ethernet network.

15. What must be in common for a BSS to form?
By short-circuiting the max age timer
Best effort delivery - integrated services model - and differentiated services model
Matching SSID - compatible data rate - authentication credentials
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

16. What is the standard for WLANs?
Cisco ILP and 802.3af
802.11
Port that connects to another switch and becomes a designated port
The distribution layer should have only L3 links

17. What is the traditional MLS view of switching?
Route once - switch many
Promiscuous and host
The RP listens to a flow's 1st packet for the dest. The SE listens to the packet and dest and puts a shortcut in the MSL cache. Netflow switching - route once - switch many
900 MHz - 2.4Ghz - and 5-6GHz

18. What routing protocols support NSF?
Time between BDPUs sent by root bridge. Default of 2 seconds
If the switch or the powered device doesn't suport power class discovery
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
BGP - EIGRP - OSPF - and IS-IS.

19. How does L3 QOS classification happen?
Group (0-1023) priority (1-255 higher better def 100)
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
The TOS field in the header is used. 2 methods 3 bits or 6 bits
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

20. where does L2 switching occur?
Between interfaces that are assigned to L2 VLANs or L2 trunks
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
An ac adaptor that plugs into a wall outlet.
Half-duplex

21. What happens when switches receive a configuration BDPU?
Almost eliminates listening and learning states for single hosts on an access link
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.
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)

22. What's the easiest way to configure GLBP timers?
1/2 and 3/6
Configure the timer on the AVG and let it propagate
FE - GE - and aggregated FE/GE Etherchannels
Half-duplex

23. How often are BDPUs sent?
2 seconds (def)
Priority (class 1)
Based on priority (0-255). Default is 100. Highest IP is tie breaker
Differentiated services code point

24. How does every HSRP config command begin?
Differentiated services
Switch(config-if)# standby xx where x= group number
80% of the user traffic should stay in the VLAN
2 seconds (def)

25. How are multiple VLANs mapped to multiple SSIDs?
26-byte header - 4-byte trailer with CRC
By using a trunk link
After forwarding delay - port can learn new MAC addresses
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

26. How do you prevent VLAN hopping?
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
300 sec by default
Stateful switchover - redundant sup is fully booted and init'd. Both start and run config are synched as is L2 information - and switchinterfaces.
Full duplex

27. What is the IEEE standard for STP?
Connects with SONET or SDH
That they aren't using the same frequencies.
Automatically by duplex mode in use. Full duplex are point ot point. Half duplex ports use traditional 802.1D convergence is used.
802.1D

28. How long are TCAM masks?
With the skinny protocol
Isl - dot1q - negotiate (default)
Transmits keystrokes from phone and commands from CCM
134 bits

29. What are the two private vlan association modes?
Promiscuous and host
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
Only on ports that have same static VLANs or trunking. It also modifies parameters of the channel if one of the ports is modified
Variation in delay

30. What does MSTP consist of?
Regions and instances
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
By using a hash of a key string
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets

31. What address does HSRP send hello packets to?
Switching Database Manager - configures and prunes TCAM partitions
224.0.0.2 (all routers)
802.11
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports

32. What are the port channel load balancing methods?
On ports where you never expect to find a root bridge for a VLAN
If the switch or the powered device doesn't suport power class discovery
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
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port

33. What is DSCP codepoint AF41(34)?
After forwarding delay - port can learn new MAC addresses
Forces the router to wait for a period of time after the switch is reloaded before attempting to overthrow
Flash override (class 4)
Trunk

34. How does an LAP bind with a WLC?
Immediate (class 2)
By brining up a tunnel between them to carry 802.11 related messages and client data.
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.
Differentiated services

35. How does RSTP identify a topology change?
Up to 4 can be used in a group. Called active virtual forwarders (AVF)
The total delay from start to finish
Based on priority (0-255). Default is 100. Highest IP is tie breaker
Only when a nonedge port transitions to forwarding

36. What do you need to determine to use MSTP?
RADIUS
Almost eliminates listening and learning states for single hosts on an access link
The standby becomes active and stays active by default. Preemption can be configured
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance

37. How does 802.1q handle COS?
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
TCAM
Needs hardware upgrade over WEP - uses AES encryption
Distributed coordinion function - the use of timers to prevent wireless collisions

38. How do you configure IP source guard for hosts that don't use DHCP?
By creating a static IP binding
Configure non-silent submode
Trunk
Forces the router to wait for a period of time before attempting overthrow

39. In a converged fabric - which switch(es) send config BDPUs?
Root
0-255
The total delay from start to finish
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

40. How do you disable DTP when you configure both ends of the ISL manually?
Yes
No
Configure and enable DHCP snooping
Switchpotrt nonegotiate

41. How does IPT behave when the voice VLAN is in untagged mode?
Port with best root path cost
Data and voice over native vlan - no QOS but still uses 802.1p trunk
No
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy

42. Can ARP replies be checked
Globally
Yes
The ASIC
A host port goes up or down

43. What is the port priority range?
0-255 (lower is better)
Yes to both
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
1- enable qos - 2-define qos parameters to be trusted - 3-make trust conditional - 4-instruct IP phone how to extnd boundary

44. Does a WLC and a LAP need to be on the same subnet?
No
Discarding - learning - forwarding
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
26-byte header - 4-byte trailer with CRC

45. How does ISL do trunking?
All nondesignated ports - but ok for all ports
By encapsulating each frame in a header and trailer
Option 43
Source IP and MAC must match those addresses learned by DHCP snooping or a static entry

46. What are the characteristics of the distribution layer?
Variation in delay
Aggregation - high L3 throughput - security and policy based connectivity functions through access lists and packet filters - QoS - scalable high-speed links
2 - one for control messages and one for data
Yes

47. How does ILP do power discovery?
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.
Globally or per-port
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.
Sends a test tone on the transmit pair. If a device is detected - CDP is used to narrow down the power class.

48. What is an MST instance?
Low cost - high density ports - multiple scalable uplinks - vlans - traffic and protocol filtering and QoS
The MST instance (MSTI) runs alongside the IST and represents an STP instance
Hosts within a secondary can communicate with each other and with the primary - but not with another secondary vlan
Used when ACLs specify port ranges...used by TCAM

49. At what layer should the WLC be connected?
7 switches from root bridge
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance
Distribution
Yes

50. What are the 3 trunk encap modes?
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
The DCF interframe space- the random backoff time before a wireless set can transmit
Data and voice over native vlan - no QOS but still uses 802.1p trunk
Isl - dot1q - negotiate (default)