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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. If a port is configured for errdisable auto recovery - how long does it stay down?
By using an Ether-IP tunnel
0-255 (lower is better)
After forwarding delay - port can learn new MAC addresses
300 sec by default

2. What if RSTP BDPUs aren't received?
1/2 and 3/6
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
L2
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged

3. What is a drop adjacency?

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4. How does DSCP handle IP precedence?
Src-dst-ip
One that can be detected on a switch interface (ie. Up/down)
All nondesignated ports - but ok for all ports
5 classes with 3 drop precedences

5. What is the 80/20 rule?
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
80% of the user traffic should stay in the VLAN

6. What is common spanning tree (CST)?
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
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode
The same as a standby group in HSRP
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based

7. What is the STP forward delay timer?
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region
Prevents the dhcp binding DB from being checked.
The time that a port spends in both listening and learning states . Default 15 seconds

8. When looking at the sh spanning tree output - What does P2P denote?
A host port goes up or down
Incoming frames dropped - but MACs learned
A point to point port type
L2

9. What is accelerated CEF (aCEF)?
Only for the offending VLAN on the port
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
5 (0-4 with 4 being the highest)

10. How much BW does a PSTN connection use?
0007.b4xx.xxyy where xx.xx is six 0 bits followed by a 10-bit GLBP group numberr. Yyyy is the virtual forwarder number
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added
63 kbps
Compatible with 802.11b - up to 54Mbps in 12 data rates - 3 channels - 2.4Ghz

11. What are the 2 choices for VLANs with IPT?
Isolated and community
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)
Used when ACLs specify port ranges...used by TCAM
By short-circuiting the max age timer

12. What is a topology change?
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac
Using a single WAP to centralize access and control over a group of wireless devices.
When a port moves into forwarding or from fowarding or learning to blocking.
Up to 4 can be used in a group. Called active virtual forwarders (AVF)

13. How is UDLD configured?
By using a trunk link
If the switch or the powered device doesn't suport power class discovery
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports

14. If a wireless station needs to transmit and another device is transmitting - what happens?
Access
Distribution layer
An AP's coverage area
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting

15. What is NSF?
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
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover
Untrusted
1500B

16. How many users should be within a switch block?
A point to point port type
Roughly 2000
A host port goes up or down
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

17. What does IP source guard do?
Makes use of the DHCP snooping database and static ip source binding entries. If enabled - switch will test addresses
The link status stays up - but something between them has failed or is filtering traffic
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
Value - mask - and result (VMR) combinations

18. What is a BSS?
Controls where candidate root bridges can be connected and found on a network
Incoming frames are dropped (combination of disabled - blocking - and listening)
By creating a static IP binding
Using a single WAP to centralize access and control over a group of wireless devices.

19. Each switch port is a _____ ______
Disabled - init - listen - speak - standby - active
Value - mask - and result (VMR) combinations
Collision domain
By default weight is 100. Can be made dynamic per interface

20. What is the range of HSRP group numbers?
0-255
Those that connect to other switches
That they aren't using the same frequencies.
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

21. What is topology-basec caching?
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
The number of times the CEF table has bee flushed and regenerated as a whole
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
802.1D

22. How are multiple VLANs mapped to multiple SSIDs?
A host port goes up or down
By using a trunk link
Trunk
Switch(config-if)# vrrp xx where xx= group number

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

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24. What are the RSTP port states?
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry
Globally
Discarding - learning - forwarding
10-15%

25. Does GLBP allow preemption?
Routers are assigned to common GLBP group. All routers can be active and can load balance
1-1005 (1 and 1002-1005 are reserved)
Switch(config-if)# vrrp xx where xx= group number
Yes

26. How many MST instances can be in a region?
By short-circuiting the max age timer
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance
Determines when the AVG will stop using the old VMAC in ARP replies

27. What are the 5 STP port roles?
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
L2
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
Root - designated - blocking - alternate - forwarding (host)

28. What are TCAM entries composed of?
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based
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
Data and voice over native vlan no QOS and no 802.1p trunk
Value - mask - and result (VMR) combinations

29. What is the port priority range?
Switch(config-if)# glbp xx where xx = group number
Turn on port security
1 per segment
0-255 (lower is better)

30. What is the RSTP default hello interval?
If the switch or the powered device doesn't suport power class discovery
2 seconds
Feature Manager - after the ACL is created - the FM compiles the ACEs into the table
Control functions

31. What are the 3 trunk encap modes?
The link status stays up - but something between them has failed or is filtering traffic
Half-duplex
Isl - dot1q - negotiate (default)
Full duplex

32. What is an IST instance?
When a port moves into forwarding or from fowarding or learning to blocking.
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.
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode
Low cost - high density ports - multiple scalable uplinks - vlans - traffic and protocol filtering and QoS

33. What does the SP do?
By default weight is 100. Can be made dynamic per interface
Time between BDPUs sent by root bridge. Default of 2 seconds
802.11
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

34. What is 802.1x force-unauthorized?
Port is forced to never authorize any connected client
3 seconds. Holdtime =3 hellos + 1
Lowest cumulative cost to root
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL

35. What types of link can an etherchannel be?
L2
Once the CCM gives them the parameters - they use RTP
If the client maintains the same IP address as it roams between Aps. All must have same VLAN - SSID - and subnet
Access or trunk

36. What is the format of the VRRP virtual MAC?
0000.5e00.01xx
Can hear only BDPUs
No shut
Used when ACLs specify port ranges...used by TCAM

37. What is the size of ISL encapsulation?
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.
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks
26-byte header - 4-byte trailer with CRC

38. How do you find duplex mismatches?
Use sh interface on the interface and look for error counts > 10
Globally
Dynamic WEP keys that change periodically
Manually

39. What are the VRRP group and priority numbers?
Group (0-255) - priority (1-254 254 is highest - 100 default)
All fiber-optic links between switches (must be enabled on both ends)
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs

40. what if a secondary VLAN?
1- enable MST - 2-enter MST config mode - 3-assign region name and region configuration rev - 4-map vlans to an MSTI - 5-show pending changes - 6- commit by exiting
Access
If the client maintains the same IP address as it roams between Aps. All must have same VLAN - SSID - and subnet
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN

41. What is integrated services model QOS?
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.
Globally
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP

42. How many links can be used in an EtherChannel?
With portfast
2 strand MMF with MT-RJ or SC connectors
2-8 FE - GE - or 10GE are bundled.
Globally

43. Does VTP pass private VLAN configuration?
If the switch or the powered device doesn't suport power class discovery
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
No
The station can transmit immediately and wait for an ack

44. What are the steps to configure a PAgP port channel?
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region
A point to point port type
134 bits - consisting of source and destination addresses and protocol information from the packet or frame

45. What do you need to determine to use MSTP?
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance
Used when ACLs specify port ranges...used by TCAM
26-byte header - 4-byte trailer with CRC

46. What is arp throttling?
LACP port priority
Based on priority (0-255). Default is 100. Highest IP is tie breaker
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
Checks the destination MAC in the header against the target MAC in the ARP reply

47. What is a VRRP group?
The same as a standby group in HSRP
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
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
Data and voice over native vlan - no QOS but still uses 802.1p trunk

48. How are GLBP timers used?
By sending a gratuitous ARP
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN
The port asks the other end to trunk

49. What scope is 802.1x enabled?
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
Any ports associated with an isolated vlan can reach the primary - but not any other secondary. Hosts withn an isolated vlan can't reach each other
Globally
Usually QoS from VOIP but not PC dataa

50. What are the restrictions for bundling into an Etherchannel?
A MAC is seen on a different port
Because each frame is checked
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings
Switch(config-if)# standby xx where x= group number