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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. What is DCF?
Trusted ports
19
TCAM
Distributed coordinion function - the use of timers to prevent wireless collisions

2. What functions does a LAP perform?
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
A MAC is seen on a different port
Only for the offending VLAN on the port
Half because transmitting and receiving stations use the same frequency

3. What is the size of a TCAM value?
Silent
134 bits - consisting of source and destination addresses and protocol information from the packet or frame
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover
Gateway load balancing protocol - cisco proprietary

4. What does MSTP do?
The station can transmit immediately and wait for an ack
Used when there are 1 or more VLANs mapped to a single STP instance
A private VLAN can be logically associated with a special secondary vlan
To the virtual port-channel interface

5. What must you be sure of if AP cells overlap?

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6. RSTP BPDU structure
After forwarding delay - port can learn new MAC addresses
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
No
By encapsulating each frame in a header and trailer

7. How can you load-balance with HSRP?
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
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server
2 - one for control messages and one for data

8. How does HSRP gateway addressing work
Hashing algorithm
Priority (class 1)
Each physical interface has a different IP address. All physical interfaces point to a virtual interface called the standby address or VIP
Port

9. What is the STP Max Age timer?
Group (0-1023) priority (1-255 higher better def 100)
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
An AP's coverage area
1 per segment

10. What is the switch block?
Enables portfast - sets the port to access and disables PAgP
No shut
Two distribution switches that aggregate one or more access switches
2 seconds (def)

11. What is an untrusted port under dhcp snooping?
A private VLAN can be logically associated with a special secondary vlan
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
1500B

12. When are RSTP bdpus sent?
All ports where root isn't expected
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
A packet can't be switched in hardware with the FIB and must go to the L3 engine
1 second. Backup routers can learn the interval from the master

13. the static port to vlan membership is handled in _____
The ASIC
134 bits
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added

14. How do you configure IP source guard for hosts that don't use DHCP?
By creating a static IP binding
Port with best root path cost
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry

15. How much BW does a PSTN connection use?
63 kbps
FIB
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block
Show standby

16. What types of authentication does HSRP allow?
Plain text or md5
1-1005 (1 and 1002-1005 are reserved)
Port is forced to never authorize any connected client
A point to point port type

17. what must be done on an SVI before it is activated?
1-(opt) set system priority - 2-select interface(s) - 3-assign the protocol - 4-set the mode - 5-(opt) set the port priority
No shut
Any ports associated with an isolated vlan can reach the primary - but not any other secondary. Hosts withn an isolated vlan can't reach each other
The station can transmit immediately and wait for an ack

18. where does L2 switching occur?
Feature Manager - after the ACL is created - the FM compiles the ACEs into the table
Port stays up - packets from violating MACs dropped - no logging
All ARP packets that arrive on untrusted ports are inspected.
Between interfaces that are assigned to L2 VLANs or L2 trunks

19. If a wireless station needs to transmit and no other device is transmitting - what happens?
No
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.
The station can transmit immediately and wait for an ack
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string

20. How does the standby handle ARP issues after it becomes active?
By sending a gratuitous ARP
Trusted or untrusted
Will trunk if asked
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

21. What is the format of the VRRP virtual MAC?
Only on ports that have same static VLANs or trunking. It also modifies parameters of the channel if one of the ports is modified
0000.5e00.01xx
Effectively stops STP on filtered ports
0-255

22. How does a LAP and a WLC authenticate between each other?
Dynamic arp inspection
Any ports associated with an isolated vlan can reach the primary - but not any other secondary. Hosts withn an isolated vlan can't reach each other
Roughly 50%
Using digital certificates

23. How much overlap should a wireless repeater have?
By name - config revision - and instance to vlan mapping table
The wireless clients communicate directly with no other means of connectivity such as a WAP
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Roughly 50%

24. How many designated ports are there?
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region
Compatible with 802.11b - up to 54Mbps in 12 data rates - 3 channels - 2.4Ghz
1 per segment
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. How can BDPU Guard be configured?
Globally or per-port
L2
300 sec by default
Because each frame is checked

26. What is the core block?

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27. FE connectors use...
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
A MAC is seen on a different port
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based
2 strand MMF with MT-RJ or SC connectors

28. What are the 5 steps to manualy configure STP?
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
Control functions
No
Port with best root path cost on segment

29. What are the port channel load balancing methods?
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port
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
Option 43
Using a mobility exchange message

30. What is the SDM?
Regions and instances
Access
Normal and aggressive
Switching Database Manager - configures and prunes TCAM partitions

31. How often are VRRP advertisements sent?
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN
Cisco recommends only on the root bridge
1 second. Backup routers can learn the interval from the master
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS

32. What is a LACP priority?
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)
Frames are forwarded
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
The ASIC

33. What is the duration time in a wireless frame?
Each frame transmits its expected duration time
Configure the timer on the AVG and let it propagate
Routers are assigned to common GLBP group. All routers can be active and can load balance
Access

34. What address does HSRP send hello packets to?
MST attributes must be manually entereed on each switch in the region. They don' t propagate like VTP.
An AP's coverage area
224.0.0.2 (all routers)
Based on priority (0-255). Default is 100. Highest IP is tie breaker

35. What types of links can be trunked?
FE - GE - and aggregated FE/GE Etherchannels
The campus network's backbone
802.11
Via an 802.1Q trunk or a single VLAN access port

36. How does every HSRP config command begin?
Switch(config-if)# standby xx where x= group number
Enables switches at the end of the spanning tree branches to have a functioning root port while keeping 1 or more redundant potential ports in blocking mode. When the main fails - the other comes up.
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config

37. What is an MST instance?
The MST instance (MSTI) runs alongside the IST and represents an STP instance
Port with redundant - but less deisrable connection to a segment. Possibly root candidate
3 seconds. Holdtime =3 hellos + 1
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance

38. What does the minimum keyword do in HSRP?
Switchpotrt nonegotiate
Forces the router to wait for a period of time before attempting overthrow
3 seconds. Holdtime =3 hellos + 1
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec

39. 802.11a
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
Up to 4 can be used in a group. Called active virtual forwarders (AVF)
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.

40. How does an L2 switch do QOS?
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy
Use the spanning-tree root macro
Based on priority (0-255). Default is 100. Highest IP is tie breaker
An L2 switch can only forward frames best effort unless going across a trunk

41. RSTP alternate port
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
Group (0-255) - priority (1-254 254 is highest - 100 default)
Switches make an effort to move packets as quickly as possible
Port with alternative path to root less desirable than root

42. What is DSCP codepoint AF21(18)?
An L2 switch can only forward frames best effort unless going across a trunk
All fiber-optic links between switches (must be enabled on both ends)
Change in trunk encap
Immediate (class 2)

43. What is the STP listening state?
Trunk
Silent
Packets must be sent to the L3 engine for further processing
Can send and receive BDPUs

44. What is UDLD normal mode?
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
When a specific interface is tracked - HSRP reduces it's priority after a specified interval.
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
Option 43

45. How does UDLD work?
An L2 switch can only forward frames best effort unless going across a trunk
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
By sending a gratuitous ARP
Using a single WAP to centralize access and control over a group of wireless devices.

46. If a wireless station needs to transmit and another device is transmitting - what happens?
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting
Port is forced to never authorize any connected client
Differentiated services code point

47. What is portfast?
Almost eliminates listening and learning states for single hosts on an access link
Automatically by duplex mode in use. Full duplex are point ot point. Half duplex ports use traditional 802.1D convergence is used.
Option 43
0000.5e00.01xx

48. What contains the next-hop entries?
On by default
19
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
FIB

49. What does the SP do?
It can't
Only when a nonedge port transitions to forwarding
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
Globally

50. What types of ports autonegotiate?
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
Control functions
Switch(config-if)# glbp xx where xx = group number
FE and GE