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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 service set?
A group of wireless devices that share a common SSID
Promiscuous and host
The TOS field in the header is used. 2 methods 3 bits or 6 bits
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack

2. What is the range of PAgP channel group numbers?
1 to 64
Critical...used most often for IPT
It's a router that maintains routes (static or dynamic) - and populates the FIB
Because each frame is checked

3. How many MST instances can be in a region?
134 bits
All fiber-optic links between switches (must be enabled on both ends)
Globally
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region

4. Where should STP timers be configured and why?
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-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
Checks the destination MAC in the header against the target MAC in the ARP reply
On root - because the root bridge propagates timers with config BDPU

5. What if RSTP BDPUs aren't received?
When the size of a cell is intentionally reduced
Virtual Router Redundancy Protocol - pretty much the same as HSRP
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
Control functions

6. What is the distribution layer best practice?
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.
Trusted ports
Port
The distribution layer should have only L3 links

7. When looking at the sh spanning tree output - What does P2P denote?
A point to point port type
No
The configureable UDLD interval must be less than max age plus two intervals of forward delay
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD

8. When should CDP be enabled?
802.1w
VTP server for domain null with no password or secure mode
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
Only for trusted Cisco gear - especially phones

9. How can you load-balance with HSRP?
It is enabled by default on all CEF capable switches
Enables portfast - sets the port to access and disables PAgP
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each

10. What is the size of ISL encapsulation?
By short-circuiting the max age timer
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy
Port that connects to another switch and becomes a designated port
26-byte header - 4-byte trailer with CRC

11. What is a bridge ID made up of?
By brining up a tunnel between them to carry 802.11 related messages and client data.
802.1x with EAP over LAN (EAPOL)
Bridge priority and MAC
Port with alternative path to root less desirable than root

12. What is the STP listening state?
On ports where you never expect to find a root bridge for a VLAN
Cisco recommends only on the root bridge
Manages addition - deletion and renaming VLANs across the network
Can send and receive BDPUs

13. What is dynamic desireable?
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
The port asks the other end to trunk
Round robin - weighted - or host-dependent
An L2 switch can only forward frames best effort unless going across a trunk

14. How does the standby handle ARP issues after it becomes active?
Untrusted
Dynamic arp inspection
By sending a gratuitous ARP
Will trunk if asked

15. How can BDPU Guard be configured?
Globally or per-port
An ac adaptor that plugs into a wall outlet.
19
Used to switch packets that can't be forwarded normallly due to an encapsulation failure - unresolved address - unsupported protocol - etc.

16. What does the skinny protocol do?
Admin down
Transmits keystrokes from phone and commands from CCM
RPR - RPR+ - and SSO
2

17. What is DSCP?
Differentiated services code point
Disabled - blocking - listening - learning - forwarding
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
If the switch or the powered device doesn't suport power class discovery

18. How does DSCP handle IP precedence?
5 classes with 3 drop precedences
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
Multicast to 01-80-c2-00-00-00
All ports where root isn't expected

19. What is the IEEE standard for STP?
Discarding - learning - forwarding
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
802.1D
2-8 FE - GE - or 10GE are bundled.

20. What is an autonomous mode AP?
Flash (class 3)
Another router must have a higher HSRP priority and have preemt set up
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac
When each AP stands alone within the larger network.

21. Where is root guard enabled?

22. Define GLBP
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
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
Gateway load balancing protocol - cisco proprietary
Connects with SONET or SDH

23. What happens when switches receive a configuration BDPU?
Group (0-1023) priority (1-255 higher better def 100)
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string
Virtual Router Redundancy Protocol - pretty much the same as HSRP

24. What is the STP learning state?
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
Configure non-silent submode
After forwarding delay - port can learn new MAC addresses
Half because transmitting and receiving stations use the same frequency

25. How long are TCAM masks?
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.
Sends a voltage across the receive pairs to detect a 25k ohm resistance
134 bits
Etherchannel ports have inconsistent config

26. How should the switch port to which a WLC be configured?
Trunk
Incoming frames are dropped (combination of disabled - blocking - and listening)
Trusted ports
Port with redundant - but less deisrable connection to a segment. Possibly root candidate

27. RSTP alternate port
Port with alternative path to root less desirable than root
Source IP and MAC must match those addresses learned by DHCP snooping or a static entry
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN
Checks the destination MAC in the header against the target MAC in the ARP reply

28. If a wireless station needs to transmit and another device is transmitting - what happens?
900 MHz - 2.4Ghz - and 5-6GHz
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN
By default weight is 100. Can be made dynamic per interface
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting

29. What is an IST instance?
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
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.
Once the CCM gives them the parameters - they use RTP
16 - of which up to 8 are active. The others are in standby

30. What is a wall wart?
An ac adaptor that plugs into a wall outlet.
1 to 64
No
Transmits keystrokes from phone and commands from CCM

31. What is NSF?
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy
Distribution layer
0-65535 (def 32768) lower=better

32. What are the 2 choices for VLANs with IPT?
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
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
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)
2-8 FE - GE - or 10GE are bundled.

33. What does the dst-mac option do when checking ARP replies
Globally
Checks the destination MAC in the header against the target MAC in the ARP reply
Receives the first packet of a traffic flow and routes it
Incoming frames dropped - but MACs learned

34. If a port is configured for errdisable auto recovery - how long does it stay down?
On root - because the root bridge propagates timers with config BDPU
300 sec by default
Limits the number if dhcp requests on a port
The number of times the entry has been updated since the table was generated

35. What is RPVST+?
Incoming frames are dropped (combination of disabled - blocking - and listening)
1-(opt) set system priority - 2-select interface(s) - 3-assign the protocol - 4-set the mode - 5-(opt) set the port priority
An instance of RSTP running for each VLAN on the switch. Changing from PVST to RPVST+ is disruptive
Between any type of interface as long as the interface can have an L3 address assigned

36. What is the acceptible range of VLANS?
Port with best root path cost on segment
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL
1-1005 (1 and 1002-1005 are reserved)
Flash (class 3)

37. What is the RSTP default hello interval?
Discarding - learning - forwarding
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
2 seconds
1/2 and 3/6

38. What does MSTP do?
Frames that barely exceed 1518B or 1622B due to headers
Globally
Used when there are 1 or more VLANs mapped to a single STP instance
The L3 forwarding engine can't forward the packet in hardware because there is no L2 next-hop address - so the packet is sent to the L3 engine to generate the ARP response

39. How does 802.3af do power discovery?
The MST instance (MSTI) runs alongside the IST and represents an STP instance
Sends a voltage across the receive pairs to detect a 25k ohm resistance
That they aren't using the same frequencies.
1 IP subnet

40. What does the switchport host macro do?
From the DHCP snooping database or from static entries
Switchpotrt nonegotiate
On the left as you face the connector
Enables portfast - sets the port to access and disables PAgP

41. How does an L2 switch do QOS?
Routers are assigned to common GLBP group. All routers can be active and can load balance
Port stays up - packets from violating MACs dropped - no logging
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry
An L2 switch can only forward frames best effort unless going across a trunk

42. What is differentiated services model QOS?
Stateful switchover - redundant sup is fully booted and init'd. Both start and run config are synched as is L2 information - and switchinterfaces.
Each network device handles packets individually with no advance reservations
RPR - RPR+ - and SSO
Usually QoS from VOIP but not PC dataa

43. How does HSRP election work?
Feature Manager - after the ACL is created - the FM compiles the ACEs into the table
Based on priority (0-255). Default is 100. Highest IP is tie breaker
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies
Port is forced to never authorize any connected client

44. What is the STP hello timer?
Time between BDPUs sent by root bridge. Default of 2 seconds
With the skinny protocol
80% of the user traffic should stay in the VLAN
All fiber-optic links between switches (must be enabled on both ends)

45. Where is the QoS trust boundary usually configured on an IP phone?
Usually QoS from VOIP but not PC dataa
Trunk - dynamic auto - dynamic desireable (default)
Isl - dot1q - negotiate (default)
Automatically negotiates a common trunk mode between switches

46. RSTP root port
Port with best root path cost
Lowest cumulative cost to root
Trunk - dynamic auto - dynamic desireable (default)
Those that connect to other switches

47. What is DSCP codepoint EF(46)?
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
It's a router that maintains routes (static or dynamic) - and populates the FIB
Critical...used most often for IPT
By short-circuiting the max age timer

48. What is step 1 of enabling IP source guard?
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
Configure and enable DHCP snooping
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information

49. Where should you change the network diameter value?
0-255
Limits the number if dhcp requests on a port
Cisco recommends only on the root bridge
SC fiber or RJ-45

50. How does RSTP converge?
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves
Globally
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based
A host port goes up or down