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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.
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. How does IPT behave when the voice VLAN is in dot1p mode?
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
It can't
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.

2. What are the 2 power over ethernet methods?
Completed dhcp bindings - mac addresses - IP addresses - etc.
1/2 and 3/6
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
Cisco ILP and 802.3af

3. 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
12 kbps with headers and compression
The port asks the other end to trunk
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS

4. How do Cisco IP phones communicate with the CCM?
Only when a nonedge port transitions to forwarding
Needs hardware upgrade over WEP - uses AES encryption
With the skinny protocol
Sends a test tone on the transmit pair. If a device is detected - CDP is used to narrow down the power class.

5. What are LOU register pairs?
Only on ports that have same static VLANs or trunking. It also modifies parameters of the channel if one of the ports is modified
Used when ACLs specify port ranges...used by TCAM
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
By encapsulating each frame in a header and trailer

6. When looking at the sh spanning tree output - What does P2P denote?
A point to point port type
Untrusted
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
300 sec

7. What address does HSRP send hello packets to?
Time between BDPUs sent by root bridge. Default of 2 seconds
If any BDUP is received on a port - it puts the port into the errdisable state
224.0.0.2 (all routers)
16 bits (8b port priority - 8b port number)

8. What is the cost of a 1Gbps link?
4
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
Controls where candidate root bridges can be connected and found on a network
Route processor redundancy - redundant sup is partially booted and initialized and must reload module in the switch and init all sup functions

9. What is a LACP priority?
Critical...used most often for IPT
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)
Port with best root path cost on segment
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD

10. What is the default VTP state?
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
VTP server for domain null with no password or secure mode
One that can be detected on a switch interface (ie. Up/down)
L2

11. Where is the QoS trust boundary usually configured on an IP phone?
Automatically using DTP and CDP
Manages addition - deletion and renaming VLANs across the network
16 bits (8b port priority - 8b port number)
Usually QoS from VOIP but not PC dataa

12. What are the 3 unlicensed frequencies?
Lowest cumulative cost to root
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies
Up to 4 can be used in a group. Called active virtual forwarders (AVF)
900 MHz - 2.4Ghz - and 5-6GHz

13. What are the 3 trunk switchport modes?
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
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
If a unidirectional link is detected - the switch doesn't try to reestablish the link. ULD msgs are sent once/sec for 8 seconds - then the port is err-disabled
Trunk - dynamic auto - dynamic desireable (default)

14. How should backbonefast be configured?
By using a trunk link
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
On all switches in network to enable RLQ request and reply
1-LAP gets a DHCP address - 2-LAP learns IP of available WLC - 3-LAP sends a join request to WLC and receives join reply - 4-WLC sends code image - if necessary - 5-Tunnels are created

15. How is the IPT 802.1 trunk negotiated?
Automatically negotiates a common trunk mode between switches
Hosts within a secondary can communicate with each other and with the primary - but not with another secondary vlan
Priority (class 1)
Automatically using DTP and CDP

16. Which 4 things must be agreeable to trunk?
Used when there are 1 or more VLANs mapped to a single STP instance
RADIUS
Needs hardware upgrade over WEP - uses AES encryption
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN

17. What happens during HSRP failover?
Route once - switch many
The standby becomes active and stays active by default. Preemption can be configured
Normal and aggressive
Checks the source MAC in the header against the sender MAC in the ARP reply

18. What is a null adjacency?
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
Used to switch packets destined for the null interface
Those that connect to other switches
When a client roams between Aps in different subnets

19. unknown unicast flooding
Root
Based on priority (0-255). Default is 100. Highest IP is tie breaker
Group (0-255) - priority (1-254 254 is highest - 100 default)
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.

20. What categories can ports be in with dhcp snooping enabled?
Differentiated services code point
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz
Trusted or untrusted
Bridge priority and MAC

21. How does an LAP bind with a WLC?
It can't
Completed dhcp bindings - mac addresses - IP addresses - etc.
1500B
By brining up a tunnel between them to carry 802.11 related messages and client data.

22. WEP encryption
Forces the router to wait for a period of time before attempting overthrow
Weak key rotation
Between interfaces that are assigned to L2 VLANs or L2 trunks
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology

23. What happens when switches receive a configuration BDPU?
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
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
Can hear only BDPUs
Needs hardware upgrade over WEP - uses AES encryption

24. What is the default network diameter?
By using a trunk link
PAgP (Cisco proprietary) and LACP (standards-based)
7 switches from root bridge
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added

25. What are the 6 HSRP states?
Variation in delay
Disabled - init - listen - speak - standby - active
2-8 FE - GE - or 10GE are bundled.
The standby becomes active and stays active by default. Preemption can be configured

26. What is the STP forwarding state?
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
A packet can't be switched in hardware with the FIB and must go to the L3 engine
When a port moves into forwarding or from fowarding or learning to blocking.
The DCF interframe space- the random backoff time before a wireless set can transmit

27. What is a cell?

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28. what I s distributed CEF (dCEF)?
CEF is distributed completely among multiple L3 forwarding engines.
PAgP (Cisco proprietary) and LACP (standards-based)
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)
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

29. Does a WLC and a LAP need to be on the same subnet?
If any BDUP is received on a port - it puts the port into the errdisable state
Based on priority (0-255). Default is 100. Highest IP is tie breaker
Two distribution switches that aggregate one or more access switches
No

30. What is the IEEE standard for STP?
802.1D
Almost eliminates listening and learning states for single hosts on an access link
Using digital certificates
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding

31. What does DTP do?
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
Automatically negotiates a common trunk mode between switches
Those that connect to other switches
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

32. What is DSCP codepoint EF(46)?
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
Critical...used most often for IPT
Aggregation - high L3 throughput - security and policy based connectivity functions through access lists and packet filters - QoS - scalable high-speed links
That they aren't using the same frequencies.

33. How often are HSRP hellos sent?
All fiber-optic links between switches (must be enabled on both ends)
3 seconds. Holdtime =3 hellos + 1
Untrusted
To the virtual port-channel interface

34. How does NSF work?
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance
Disabled - init - listen - speak - standby - active
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
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

35. If a wireless station needs to transmit and another device is transmitting - what happens?
Receives the first packet of a traffic flow and routes it
Switch(config-if)# vrrp xx where xx= group number
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting
When the size of a cell is intentionally reduced

36. How does L3 QOS classification happen?
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)
Gateway load balancing protocol - cisco proprietary
0-255
The TOS field in the header is used. 2 methods 3 bits or 6 bits

37. How many 802.3af power classes are there?
By short-circuiting the max age timer
No because they only participate if asked
5 (0-4 with 4 being the highest)
L2

38. RSTP uses which standard?
Access
The wireless clients communicate directly with no other means of connectivity such as a WAP
802.1w
Used to switch packets that can't be forwarded normallly due to an encapsulation failure - unresolved address - unsupported protocol - etc.

39. What is a bridge ID made up of?
Bridge priority and MAC
Cisco recommends only on the root bridge
Access
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

40. How do you configure a DHCP gateway?
Interim solution - uses same hardware as WEP - but uses TKIP encryption
Variation in delay
Regions and instances
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server

41. EAP encryption
On the left as you face the connector
Routers are assigned to common GLBP group. All routers can be active and can load balance
Real-time Transport Protocol
Dynamic WEP keys that change periodically

42. what if a secondary VLAN?
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN
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
Use sh interface on the interface and look for error counts > 10
A client can roam to any WLC as long as it stays in a mobility group

43. How does ISL do trunking?
Yes
By encapsulating each frame in a header and trailer
Port with best root path cost
Globally or per-port

44. What contains the next-hop entries?
Once the CCM gives them the parameters - they use RTP
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Data and voice over native vlan - no QOS but still uses 802.1p trunk
FIB

45. How many MST instances can be in a region?
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region
Used to switch packets that can't be forwarded normallly due to an encapsulation failure - unresolved address - unsupported protocol - etc.
Regions and instances
Group (0-1023) priority (1-255 higher better def 100)

46. How can you tell if a switch block is too large?
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block
A host port goes up or down
Route processor redundancy - redundant sup is partially booted and initialized and must reload module in the switch and init all sup functions
Disabled - blocking - listening - learning - forwarding

47. What is a QoS trust boundary?
RADIUS
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
26-byte header - 4-byte trailer with CRC
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client

48. When a host is connected to a switchport - why aren't frame errors propagated?
Trunk - dynamic auto - dynamic desireable (default)
The wireless clients communicate directly with no other means of connectivity such as a WAP
Admin down
Because each frame is checked

49. Where is loop guard enabled?
Root - designated - alternate - and backup
Half-duplex
All nondesignated ports - but ok for all ports
16 bits (8b port priority - 8b port number)

50. Can MSTP interoperate with 802.1q and/or PVST+?
Transmits keystrokes from phone and commands from CCM
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.
All nondesignated ports - but ok for all ports
Yes to both