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 DSCP codepoint AF21(18)?
Immediate (class 2)
Port with alternative path to root less desirable than root
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
By creating a static IP binding


2. What is SSO?

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3. How does HSRP plain text authentication work?
On root - because the root bridge propagates timers with config BDPU
A key string of up to 8 characters is sent. Default is cisco.
Multicasts to 224.0.0.18 (VRRP)
As a VLAN access map


4. How are VACLs configured?
As a VLAN access map
Checks the source MAC in the header against the sender MAC in the ARP reply
Using a mobility exchange message
The TOS field in the header is used. 2 methods 3 bits or 6 bits


5. How does UDLD work?
Regions and instances
Only a single host connects . If one BDPU is received - it is no longer an edge port
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
Globally


6. What is backbonefast?
1 IP subnet
Prevents the dhcp binding DB from being checked.
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
134 bits


7. What is the STP hello timer?
Time between BDPUs sent by root bridge. Default of 2 seconds
5 classes with 3 drop precedences
Almost eliminates listening and learning states for single hosts on an access link
3 seconds. Holdtime =3 hellos + 1


8. Where does VRRP send advertisements?
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
Multicasts to 224.0.0.18 (VRRP)
Auto mode
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting


9. What is a CEF punt?

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10. What are the steps of RSTP convergence?
16 bits (8b port priority - 8b port number)
1- root bridge is elected - 2-the state of eery switch port in the STP domain must be brought from blocking state to the appropriate state
134 bits
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.


11. What is the STP learning state?
After forwarding delay - port can learn new MAC addresses
5 (0-4 with 4 being the highest)
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
900 MHz - 2.4Ghz - and 5-6GHz


12. What is a wall wart?
An ac adaptor that plugs into a wall outlet.
5 classes with 3 drop precedences
Root
If any BDUP is received on a port - it puts the port into the errdisable state


13. What is the size of a TCAM value?
Discarding - learning - forwarding
FE and GE
When each AP stands alone within the larger network.
134 bits - consisting of source and destination addresses and protocol information from the packet or frame


14. What is DSCP codepoint EF(46)?
Forces the router to wait for a period of time before attempting overthrow
The active router. All other routers are in backup state
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL
Critical...used most often for IPT


15. Where is root guard enabled?

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16. What are the gotchas for uplinkfast?

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17. How does the standby handle ARP issues after it becomes active?
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Data and voice over native vlan no QOS and no 802.1p trunk
By sending a gratuitous ARP


18. What are the 5 STP states?
Determines when the AVG will stop using the old VMAC in ARP replies
Disabled - blocking - listening - learning - forwarding
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
An L2 switch can only forward frames best effort unless going across a trunk


19. What is a null adjacency?
With the skinny protocol
Based on priority (0-255). Default is 100. Highest IP is tie breaker
Used to switch packets destined for the null interface
1 per segment


20. What functions does a LAP perform?
Receives the first packet of a traffic flow and routes it
Isolated and community
When each AP stands alone within the larger network.
Real-time functions such as beacons and probes - encryption and interactions with the client at L2


21. What are spoofed addresses?
Both layer 2 switching and IVR
Half-duplex
26-byte header - 4-byte trailer with CRC
They disguise the origin of an attack


22. What does the dst-mac option do when checking ARP replies
Checks the destination MAC in the header against the target MAC in the ARP reply
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
Transmits keystrokes from phone and commands from CCM
3 seconds. Holdtime =3 hellos + 1


23. What is the GLBP group and priority range
FIB
Group (0-1023) priority (1-255 higher better def 100)
Hashing algorithm
Between any type of interface as long as the interface can have an L3 address assigned


24. How does an L2 switch do QOS?
Because each frame is checked
2 seconds
Only when a nonedge port transitions to forwarding
An L2 switch can only forward frames best effort unless going across a trunk


25. What functions does a WLC perform?
Data and voice over native vlan - no QOS but still uses 802.1p trunk
5 classes with 3 drop precedences
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
Control functions


26. How do you renable an err-disable port by default?
Manually
Automatically negotiates a common trunk mode between switches
1 IP subnet
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains


27. What's the easiest way to configure GLBP timers?
Trunk
The ASIC
Limits the number if dhcp requests on a port
Configure the timer on the AVG and let it propagate


28. What is DAI?
Manually
Between any type of interface as long as the interface can have an L3 address assigned
Dynamic arp inspection
They should be an unconditional Etherchannel because the WLC can't negotiate a channel.


29. What is the core block?

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30. What format does the GLBP MAC use?
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
1-(opt) set system priority - 2-select interface(s) - 3-assign the protocol - 4-set the mode - 5-(opt) set the port priority
0007.b4xx.xxyy where xx.xx is six 0 bits followed by a 10-bit GLBP group numberr. Yyyy is the virtual forwarder number
If any BDUP is received on a port - it puts the port into the errdisable state


31. How does loop guard block ports?
Configure non-silent submode
0-255
Only for the offending VLAN on the port
Best effort delivery - integrated services model - and differentiated services model


32. What are 2 ways to configure VLAN and VTP information?
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string
Port is forced to never authorize any connected client
With the skinny protocol
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy


33. What are the three basic types of QOS?
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
Yes
Best effort delivery - integrated services model - and differentiated services model
Dynamic arp inspection


34. What is the STP disabled state?
Admin down
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
FE and GE


35. What is a BSS?
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves
Using a single WAP to centralize access and control over a group of wireless devices.
The TOS field in the header is used. 2 methods 3 bits or 6 bits
19


36. How does IPT behave when the voice VLAN is in untagged mode?
Forces the router to wait for a period of time before attempting overthrow
Yes to both
Data and voice over native vlan - no QOS but still uses 802.1p trunk
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q


37. What does DTP do?
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
Using a single WAP to centralize access and control over a group of wireless devices.
When a specific interface is tracked - HSRP reduces it's priority after a specified interval.
Automatically negotiates a common trunk mode between switches


38. RSTP backup port
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
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
Immediate (class 2)
Port with redundant - but less deisrable connection to a segment. Possibly root candidate


39. What does the RP do?
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN
A VLAN that spans the entire fabric
Use sh interface on the interface and look for error counts > 10
Receives the first packet of a traffic flow and routes it


40. How are GLBP timers used?
1-65535 (def 32768) lower priority - higher probability
Yes
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
Control functions


41. What are the restrictions for bundling into an Etherchannel?
Round robin - weighted - or host-dependent
To the virtual port-channel interface
On ports where you never expect to find a root bridge for a VLAN
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings


42. What is route caching?

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43. What are the 3 trunk encap modes?
Isl - dot1q - negotiate (default)
Half-duplex
Switch(config-if)# vrrp xx where xx= group number
Embeds the tag within the frame


44. What is the default network diameter?
7 switches from root bridge
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings
The same as a standby group in HSRP
Arp for local subnet - if on different subnet - will arp for dgw


45. What is UDLD normal mode?
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
With portfast
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
BGP - EIGRP - OSPF - and IS-IS.


46. What is a QoS trust boundary?
Another router must have a higher HSRP priority and have preemt set up
Missed beacons - dropped packets (max retry) - weak signal (data rate switches down) - an AP periodicallytries to find a stronger signal
Lowest cumulative cost to root
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP


47. What is portfast?
All nondesignated ports - but ok for all ports
The MST instance (MSTI) runs alongside the IST and represents an STP instance
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
Almost eliminates listening and learning states for single hosts on an access link


48. How are errdisable triggers tuned?
L2
Globally
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information


49. What is a discard adjacency?
FE - GE - and aggregated FE/GE Etherchannels
With portfast
Packets are discarded due to an ACL or policy action
Using a mobility exchange message


50. What are the 3 RSTP port types?
802.1w
802.1D
Edge - root - and point to point
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN