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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. What must be supported for port-based security to occur?
224.0.0.2 (all routers)
802.1x with EAP over LAN (EAPOL)
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added
By short-circuiting the max age timer

2. What is the GLBP redirect timer?
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
802.1D
Determines when the AVG will stop using the old VMAC in ARP replies
The same as a standby group in HSRP

3. What is 802.1x force-authorized?
Best effort delivery - integrated services model - and differentiated services model
Incoming frames dropped - but MACs learned
The port is forced to always authorize any connected client with no authentication necessary (default)
Switched Virtual Interface - an L3 address can be assigned to a logical interface that represents an entire VLAN - which becomes the DGW for that VLAN

4. What does the epoch number indicate when looking at cef entries?
Switch(config-if)# glbp xx where xx = group number
When a specific interface is tracked - HSRP reduces it's priority after a specified interval.
Switchpotrt nonegotiate
The number of times the CEF table has bee flushed and regenerated as a whole

5. What is an indirect topology change?
Plain text or md5
The link status stays up - but something between them has failed or is filtering traffic
Used when there are 1 or more VLANs mapped to a single STP instance
By name - config revision - and instance to vlan mapping table

6. How does a Cisco IP phone connect upstream?
Every switch and router in a network must be configured with appropriate QoS features and policies
Checks the source MAC in the header against the sender MAC in the ARP reply
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
Via an 802.1Q trunk or a single VLAN access port

7. What are the characteristics of the distribution layer?
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge
900 MHz - 2.4Ghz - and 5-6GHz
Source IP and MAC must match those addresses learned by DHCP snooping or a static entry
Aggregation - high L3 throughput - security and policy based connectivity functions through access lists and packet filters - QoS - scalable high-speed links

8. What is the size of a TCAM value?
Disabled - init - listen - speak - standby - active
134 bits - consisting of source and destination addresses and protocol information from the packet or frame
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds

9. When are RSTP bdpus sent?
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
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
Multicast to 01-80-c2-00-00-00

10. What does Loop Guard do?
Globally
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks
5 classes with 3 drop precedences
A point to point port type but the neighboring device runs traditional 802.1D STP

11. What is the default VTP state?
Determines when the AVG will stop using the old VMAC in ARP replies
VTP server for domain null with no password or secure mode
By an ARP access list that defines the permitted bindings
No

12. What is the cost of a 10Gbps link?
2
1 per segment
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string
The port is forced to always authorize any connected client with no authentication necessary (default)

13. What is DAI?
Dynamic arp inspection
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
Port that connects to another switch and becomes a designated port
Sends a voltage across the receive pairs to detect a 25k ohm resistance

14. How much BW does a voip connection use?
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
Feature Manager - after the ACL is created - the FM compiles the ACEs into the table
12 kbps with headers and compression
Yes

15. What is a service set?
Connects with SONET or SDH
When the size of a cell is intentionally reduced
A client can roam to any WLC as long as it stays in a mobility group
A group of wireless devices that share a common SSID

16. What is a QoS trust boundary?
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
Missed beacons - dropped packets (max retry) - weak signal (data rate switches down) - an AP periodicallytries to find a stronger signal
A point to point port type
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

17. By default - what layer do catalyst switchports operate on?
Each network device handles packets individually with no advance reservations
L2
Hosts within a secondary can communicate with each other and with the primary - but not with another secondary vlan
Change in trunk encap

18. What does DTP do?
The active router. All other routers are in backup state
Once the CCM gives them the parameters - they use RTP
Automatically negotiates a common trunk mode between switches
Both layer 2 switching and IVR

19. the static port to vlan membership is handled in _____
Manually
Show standby
The ASIC
By using a hash of a key string

20. What is a VRRP group?
The port is forced to always authorize any connected client with no authentication necessary (default)
The same as a standby group in HSRP
An ac adaptor that plugs into a wall outlet.
Embeds the tag within the frame

21. How do you prevent VLAN hopping?
Group (0-255) - priority (1-254 254 is highest - 100 default)
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
Value - mask - and result (VMR) combinations
0007.b4xx.xxyy where xx.xx is six 0 bits followed by a 10-bit GLBP group numberr. Yyyy is the virtual forwarder number

22. What is the switch block?
Manually
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
5 (0-4 with 4 being the highest)
Two distribution switches that aggregate one or more access switches

23. What functions does a LAP perform?
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
Arp for local subnet - if on different subnet - will arp for dgw
Dynamic WEP keys that change periodically
1-1005 (1 and 1002-1005 are reserved)

24. How does NSF work?
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)
Critical...used most often for IPT
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance
0007.b4xx.xxyy where xx.xx is six 0 bits followed by a 10-bit GLBP group numberr. Yyyy is the virtual forwarder number

25. What is a vlan?
The number of times the CEF table has bee flushed and regenerated as a whole
Data and voice over native vlan no QOS and no 802.1p trunk
A point to point port type but the neighboring device runs traditional 802.1D STP
A single broadcast domain

26. How are GLBP timers used?
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
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
300 sec by default
0000.0c07.acxx where xx is the group number as a 2-digit hex value

27. What is an MST instance?
Arp for local subnet - if on different subnet - will arp for dgw
The MST instance (MSTI) runs alongside the IST and represents an STP instance
900 MHz - 2.4Ghz - and 5-6GHz
0-255

28. How do VRRP routers handle preemption?
On by default
FE - GE - and aggregated FE/GE Etherchannels
3 seconds. Holdtime =3 hellos + 1
No shut

29. What does Root Guard do?
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.
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
Variation in delay
Controls where candidate root bridges can be connected and found on a network

30. What is the STP learning state?
Routers are assigned to common GLBP group. All routers can be active and can load balance
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
Each physical interface has a different IP address. All physical interfaces point to a virtual interface called the standby address or VIP
After forwarding delay - port can learn new MAC addresses

31. What is an IBSS?
1-1005 (1 and 1002-1005 are reserved)
Turn on port security
The wireless clients communicate directly with no other means of connectivity such as a WAP
300 sec

32. 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
Port
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port
No

33. How are errdisable triggers tuned?
By using a hash of a key string
When the size of a cell is intentionally reduced
Globally
Those that connect to other switches

34. What are the three basic types of QOS?
Automatically by duplex mode in use. Full duplex are point ot point. Half duplex ports use traditional 802.1D convergence is used.
It can't
Best effort delivery - integrated services model - and differentiated services model
300 sec

35. What is errdisable dtp-flap?
Change in trunk encap
Only for the offending VLAN on the port
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings

36. At what layer does EAPOL run?
L2
5 classes with 3 drop precedences
Both layer 2 switching and IVR
It can't

37. What is the FM?
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client
Feature Manager - after the ACL is created - the FM compiles the ACEs into the table
When each AP stands alone within the larger network.

38. What are the restrictions for bundling into an Etherchannel?
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
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
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings

39. Which 4 things must be agreeable to trunk?
The distribution layer should have only L3 links
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN
19
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

40. What is unique about HSRP group numbers?
Isolated and community
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
Globally
SC fiber or RJ-45

41. What duplex setting does 802.11 use and why?
1/2 and 3/6
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
Half because transmitting and receiving stations use the same frequency

42. What is a LACP priority?
On ports where you never expect to find a root bridge for a VLAN
LACP port priority
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)

43. When DHCP snooping is turned on - by default - it considers all ports ______
Untrusted
80% of the user traffic should stay in the VLAN
An AP's coverage area
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen

44. What is a root link query (RLQ)?
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge
Route once - switch many
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
Port that connects to another switch and becomes a designated port

45. How often are BDPUs sent?
2 seconds (def)
63 kbps
Disabled - blocking - listening - learning - forwarding
If the switch or the powered device doesn't suport power class discovery

46. What is the STP disabled state?
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
Almost eliminates listening and learning states for single hosts on an access link
Admin down
Hashing algorithm

47. What is an insignificant topology change?
Group (0-1023) priority (1-255 higher better def 100)
5 classes with 3 drop precedences
A host port goes up or down
Full duplex

48. How often are HSRP hellos sent?
3 seconds. Holdtime =3 hellos + 1
Between any type of interface as long as the interface can have an L3 address assigned
It is enabled by default on all CEF capable switches
1 IP subnet

49. What does the standby HSRP router do?
Only the standby monitors the hello messages from the active router
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge

50. How should backbonefast be configured?
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
On all switches in network to enable RLQ request and reply
Packets must be sent to the L3 engine for further processing
Based on priority (0-255). Default is 100. Highest IP is tie breaker