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 is a proxy arp?

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2. Does GLBP allow preemption?
By encapsulating each frame in a header and trailer
Yes
Packets are discarded due to an ACL or policy action
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port


3. What is the range of PAgP channel group numbers?
No
By brining up a tunnel between them to carry 802.11 related messages and client data.
By using an Ether-IP tunnel
1 to 64


4. What is BDPU Guard?
Immediate (class 2)
If any BDUP is received on a port - it puts the port into the errdisable state
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
Route once - switch many


5. What does the version number indicate when looking at CEF entries?
The number of times the entry has been updated since the table was generated
By using a hash of a key string
16 bits (8b port priority - 8b port number)
SC fiber or RJ-45


6. CAM table entries are purged when....
A MAC is seen on a different port
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
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
1-1005 (1 and 1002-1005 are reserved)


7. How is an instance defined?
By name - config revision - and instance to vlan mapping table
Port is forced to never authorize any connected client
No because they only participate if asked
The time that a port spends in both listening and learning states . Default 15 seconds


8. What is DSCP codepoint EF(46)?
Will trunk if asked
Both ends should be on because on modes doesn't send PAgP or LACP packets
The number of times the entry has been updated since the table was generated
Critical...used most often for IPT


9. What does the src-mac option do when checking ARP replies
The same as a standby group in HSRP
Regions and instances
Used when there are 1 or more VLANs mapped to a single STP instance
Checks the source MAC in the header against the sender MAC in the ARP reply


10. When a host is connected to a switchport - why aren't frame errors propagated?
Root - designated - alternate - and backup
Only on ports that have same static VLANs or trunking. It also modifies parameters of the channel if one of the ports is modified
Almost eliminates listening and learning states for single hosts on an access link
Because each frame is checked


11. What is 802.1x auto?
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client
0007.b4xx.xxyy where xx.xx is six 0 bits followed by a 10-bit GLBP group numberr. Yyyy is the virtual forwarder number
5 classes with 3 drop precedences
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


12. How can you tell if a switch block is too large?
To a VLAN and not to a VLAN interface (SVI)
Local only
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block
Roughly 2000


13. How do you disable DTP when you configure both ends of the ISL manually?
Switchpotrt nonegotiate
1/2 and 3/6
Route processor redundancy - redundant sup is partially booted and initialized and must reload module in the switch and init all sup functions
Manages addition - deletion and renaming VLANs across the network


14. What is layer 2 roaming?
Dynamic arp inspection
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
If the client maintains the same IP address as it roams between Aps. All must have same VLAN - SSID - and subnet
When the AP uplinks to an Ethernet network.


15. How is a QoS trust bondary configured?
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
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 brining up a tunnel between them to carry 802.11 related messages and client data.
Every switch and router in a network must be configured with appropriate QoS features and policies


16. What is the GLBP group and priority range
Group (0-1023) priority (1-255 higher better def 100)
Port with best root path cost on segment
VTP server for domain null with no password or secure mode
An ac adaptor that plugs into a wall outlet.


17. What is the default FE duplex?
2
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
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
Full duplex


18. Where is bdpu guard enabled?
All user ports that have portfast enabled
Port with alternative path to root less desirable than root
On root - because the root bridge propagates timers with config BDPU
Yes


19. What is the STP listening state?
Transmits keystrokes from phone and commands from CCM
Can send and receive BDPUs
Receives the first packet of a traffic flow and routes it
Change in trunk encap


20. How many designated ports are there?
Promiscuous and host
1 per segment
Used when there are 1 or more VLANs mapped to a single STP instance
Change in trunk encap


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

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22. What format does the GLBP MAC use?
With portfast
Half-duplex
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 seconds


23. What is dynamic auto?
No
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string
Will trunk if asked
The station can transmit immediately and wait for an ack


24. What if RSTP BDPUs aren't received?
Route once - switch many
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
FE and GE
1-1005 (1 and 1002-1005 are reserved)


25. How does HSRP election work?
Frames that barely exceed 1518B or 1622B due to headers
By an ARP access list that defines the permitted bindings
Automatically using DTP and CDP
Based on priority (0-255). Default is 100. Highest IP is tie breaker


26. What do you need to determine to use MSTP?
Roughly 50%
Checks the destination MAC in the header against the target MAC in the ARP reply
Disabled - init - listen - speak - standby - active
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance


27. How many users should be within a switch block?
Roughly 2000
Trunk - dynamic auto - dynamic desireable (default)
A packet can't be switched in hardware with the FIB and must go to the L3 engine
The number of times the CEF table has bee flushed and regenerated as a whole


28. What does IP source guard do?
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server
Another router must have a higher HSRP priority and have preemt set up
Packets are discarded due to an ACL or policy action
Makes use of the DHCP snooping database and static ip source binding entries. If enabled - switch will test addresses


29. What are the 2 UDLD modes?
A point to point port type but the neighboring device runs traditional 802.1D STP
Each network device handles packets individually with no advance reservations
Normal and aggressive
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


30. What is the default 802.3af power class and its use?

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31. What is the size of a TCAM value?
All L2 connectivity should be contained within the access layer.
FE - GE - and aggregated FE/GE Etherchannels
2 seconds (def)
134 bits - consisting of source and destination addresses and protocol information from the packet or frame


32. What are the 3 unlicensed frequencies?
Group (0-255) - priority (1-254 254 is highest - 100 default)
The station can transmit immediately and wait for an ack
900 MHz - 2.4Ghz - and 5-6GHz
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


33. What does the RP do?
Receives the first packet of a traffic flow and routes it
900 MHz - 2.4Ghz - and 5-6GHz
Switch(config-if)# standby xx where x= group number
Route processor redundancy - redundant sup is partially booted and initialized and must reload module in the switch and init all sup functions


34. What does the skinny protocol do?
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based
Transmits keystrokes from phone and commands from CCM
Value - mask - and result (VMR) combinations
Via an 802.1Q trunk or a single VLAN access port


35. What is the RSTP default hello interval?
134 bits
1 second. Backup routers can learn the interval from the master
2 seconds
Roughly 50%


36. What is route caching?

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37. What is portfast?
Almost eliminates listening and learning states for single hosts on an access link
Completed dhcp bindings - mac addresses - IP addresses - etc.
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode
802.1w


38. How do you show HSRP status
1-65535 (def 32768) lower priority - higher probability
Promiscuous and host
Show standby
Change in trunk encap


39. Does VTP pass private VLAN configuration?
No
10-15%
Transmits keystrokes from phone and commands from CCM
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers


40. If you want IP source guard to detect spoofed MAC addresses - what must you do?
1-65535 (def 32768) lower priority - higher probability
Virtual Router Redundancy Protocol - pretty much the same as HSRP
Turn on port security
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode


41. How does every VRRP command begin?
Multicasts to 224.0.0.18 (VRRP)
Plain text or md5
Port is forced to never authorize any connected client
Switch(config-if)# vrrp xx where xx= group number


42. Can two switches in the auto(PAgP) or passive (LACP) mode create a channel? Why?
No because they only participate if asked
1 second. Backup routers can learn the interval from the master
300 sec by default
By creating a static IP binding


43. What criteria are used to size a switch block?
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
The distribution layer should have only L3 links
FIB


44. What are the characteristics of the core layer
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
Local only
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Isolated and community


45. What are the 4 steps to extend QoS trust?
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
1- enable qos - 2-define qos parameters to be trusted - 3-make trust conditional - 4-instruct IP phone how to extnd boundary
TCAM
4


46. What is DCF?
Half-duplex
When a specific interface is tracked - HSRP reduces it's priority after a specified interval.
Because each frame is checked
Distributed coordinion function - the use of timers to prevent wireless collisions


47. How does adding option-82 to DHCP snooping affect things?

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48. can root guard and loop guard be used together
All nondesignated ports - but ok for all ports
Matching SSID - compatible data rate - authentication credentials
No
1 IP subnet


49. How is a WLC handoff handled when the WLCs are in different subnets?
By brining up a tunnel between them to carry 802.11 related messages and client data.
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
By using an Ether-IP tunnel
0-255 (lower is better)


50. What are the 4 steps in DHCP negotiation?
Roughly 50%
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.
Prevents the dhcp binding DB from being checked.
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack