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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 are the three basic types of QOS?
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
Best effort delivery - integrated services model - and differentiated services model
By name - config revision - and instance to vlan mapping table
By default weight is 100. Can be made dynamic per interface

2. What must be in common for a BSS to form?
16 - IST gets MSTI 0 - 1-15 are available for use. MSTIs are locally significant to the MST region
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
Matching SSID - compatible data rate - authentication credentials
Immediate (class 2)

3. What is route caching?

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4. How does a DAI enabled switch gather trusted ARP info?
Globally
From the DHCP snooping database or from static entries
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
Port

5. How does loop guard block ports?
A point to point port type but the neighboring device runs traditional 802.1D STP
The standby becomes active and stays active by default. Preemption can be configured
Only for the offending VLAN on the port
0-65535 (def 32768) lower=better

6. What types of link can an etherchannel be?
Globally
Switchpotrt nonegotiate
Multicasts to 224.0.0.18 (VRRP)
Access or trunk

7. 802.11g
Configure and enable DHCP snooping
LACP port priority
Globally or per-port
Compatible with 802.11b - up to 54Mbps in 12 data rates - 3 channels - 2.4Ghz

8. How is the HSRP MAC address configured?
Isl - dot1q - negotiate (default)
Forces the router to wait for a period of time before attempting overthrow
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
0000.0c07.acxx where xx is the group number as a 2-digit hex value

9. What is the STP forward delay timer?
The time that a port spends in both listening and learning states . Default 15 seconds
Transmits keystrokes from phone and commands from CCM
Can hear only BDPUs
Auto mode

10. What does Root Guard do?
When the AP uplinks to an Ethernet network.
Controls where candidate root bridges can be connected and found on a network
Access or trunk
2

11. Of what significance are private VLANs
Local only
Port with best root path cost on segment
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
Source IP and MAC must match those addresses learned by DHCP snooping or a static entry

12. What does Loop Guard do?
Makes use of the DHCP snooping database and static ip source binding entries. If enabled - switch will test addresses
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks
When a client roams between Aps in different subnets

13. What is a punt adjacency?
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
Between interfaces that are assigned to L2 VLANs or L2 trunks
If any BDUP is received on a port - it puts the port into the errdisable state
Packets must be sent to the L3 engine for further processing

14. How is a QoS trust bondary configured?
Every switch and router in a network must be configured with appropriate QoS features and policies
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
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
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p

15. what I s distributed CEF (dCEF)?
With portfast
CEF is distributed completely among multiple L3 forwarding engines.
The DCF interframe space- the random backoff time before a wireless set can transmit
To a VLAN and not to a VLAN interface (SVI)

16. How do IP phones communicate with each other?
Once the CCM gives them the parameters - they use RTP
1-enable AAA on switch - 2-define RADIUS servers - 3-define authentication method - 4-enable 802.1x on switch - 5-conf. 802.1x ports - 6-allow hosts
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
RADIUS

17. RSTP point to point port
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
Port that connects to another switch and becomes a designated port
A TCN BDPU is sent out of the switch's root port. The switch will continue sending TCN's every hello interval until ack'd by upstream neighbor. The root bridge will send a Config BDPU to all switches
By name - config revision - and instance to vlan mapping table

18. How can BDPU Guard be configured?
By using a hash of a key string
Roughly 2000
Globally or per-port
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

19. Define HSRP
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
2

20. What is the cost of a 100Mbps link?
19
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
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
After forwarding delay - port can learn new MAC addresses

21. How are VACLs applied
To a VLAN and not to a VLAN interface (SVI)
3 seconds. Holdtime =3 hellos + 1
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config

22. What routing protocols support NSF?
BGP - EIGRP - OSPF - and IS-IS.
Port with best root path cost
1-65535 (def 32768) lower priority - higher probability
1 to 64

23. What is errdisable dtp-flap?
Configuration and TCN
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
Root - designated - blocking - alternate - forwarding (host)
Change in trunk encap

24. What is the STP blocking state?
By using a hash of a key string
Port that connects to another switch and becomes a designated port
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
Can hear only BDPUs

25. What is the STP Max Age timer?
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
When the size of a cell is intentionally reduced
1-enable AAA on switch - 2-define RADIUS servers - 3-define authentication method - 4-enable 802.1x on switch - 5-conf. 802.1x ports - 6-allow hosts
L2

26. What does BDPU filtering do?
Variation in delay
Effectively stops STP on filtered ports
224.0.0.2 (all routers)
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks

27. How does ISL handle COS?
Only when a nonedge port transitions to forwarding
Interim solution - uses same hardware as WEP - but uses TKIP encryption
By brining up a tunnel between them to carry 802.11 related messages and client data.
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)

28. How is 802.1x configured for port security?
Missed beacons - dropped packets (max retry) - weak signal (data rate switches down) - an AP periodicallytries to find a stronger signal
CEF is distributed completely among multiple L3 forwarding engines.
RADIUS
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)

29. What are the 3 ways GLBP load-balances?
To a VLAN and not to a VLAN interface (SVI)
Access or trunk
From the DHCP snooping database or from static entries
Round robin - weighted - or host-dependent

30. What contains the next-hop entries?
Via an 802.1Q trunk or a single VLAN access port
If any BDUP is received on a port - it puts the port into the errdisable state
The configureable UDLD interval must be less than max age plus two intervals of forward delay
FIB

31. How does Root Guard work?

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32. How many potential links can LACP define?
Virtual Router Redundancy Protocol - pretty much the same as HSRP
Real-time Transport Protocol
16 - of which up to 8 are active. The others are in standby
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.

33. What does the switchport host macro do?
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port
802.1x with EAP over LAN (EAPOL)
Limits the number if dhcp requests on a port
If the switch or the powered device doesn't suport power class discovery

34. Define GLBP
Gateway load balancing protocol - cisco proprietary
Connects with SONET or SDH
802.11
Both layer 2 switching and IVR

35. What is portfast?
Almost eliminates listening and learning states for single hosts on an access link
Incoming frames are dropped (combination of disabled - blocking - and listening)
1-1005 (1 and 1002-1005 are reserved)
Switch(config-if)# glbp xx where xx = group number

36. What happens when an ARP reply is received on an untrusted port?

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37. What is an indirect topology change?
Trusted ports
Isolated and community
The link status stays up - but something between them has failed or is filtering traffic
An instance of RSTP running for each VLAN on the switch. Changing from PVST to RPVST+ is disruptive

38. What is the DIFS?
Automatically negotiates a common trunk mode between switches
The DCF interframe space- the random backoff time before a wireless set can transmit
Switching Database Manager - configures and prunes TCAM partitions
By an ARP access list that defines the permitted bindings

39. How do you configure DAI for statically configured IP addresses?
By an ARP access list that defines the permitted bindings
Sends a voltage across the receive pairs to detect a 25k ohm resistance
2 - one for control messages and one for data
10-15%

40. How many users should be within a switch block?
16 - of which up to 8 are active. The others are in standby
Packets are discarded due to an ACL or policy action
Roughly 2000
On root - because the root bridge propagates timers with config BDPU

41. What is the distribution layer best practice?
FE - GE - and aggregated FE/GE Etherchannels
The distribution layer should have only L3 links
Src-dst-ip
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance

42. How do Cisco IP phones communicate with the CCM?
Disabled - blocking - listening - learning - forwarding
With the skinny protocol
Configure and enable DHCP snooping
Frames are forwarded

43. If one end of an Etherchannel (either type) is set to on and the channel doesn't form - what should you check?

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44. When a host is connected to a switchport - why aren't frame errors propagated?
Because each frame is checked
Trunk
1-65535 (def 32768) lower priority - higher probability
Isolated and community

45. What is a QoS trust boundary?
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
Manually
LWAPP (Cisco proprietary) and CAP-WAP (standards based)
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.

46. What is the 80/20 rule?
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
It is enabled by default on all CEF capable switches
80% of the user traffic should stay in the VLAN

47. What are the RSTP port states?
Discarding - learning - forwarding
Needs hardware upgrade over WEP - uses AES encryption
The TOS field in the header is used. 2 methods 3 bits or 6 bits
19

48. How does DAI work?
All ARP packets that arrive on untrusted ports are inspected.
802.1w
No
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets

49. What is the STP learning state?
Two distribution switches that aggregate one or more access switches
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
After forwarding delay - port can learn new MAC addresses
Needs hardware upgrade over WEP - uses AES encryption

50. CAM table entries are purged when....
A MAC is seen on a different port
The link status stays up - but something between them has failed or is filtering traffic
Control functions
Both ends should be on because on modes doesn't send PAgP or LACP packets