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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 does VTP do?
Port
Manages addition - deletion and renaming VLANs across the network
2 - one for control messages and one for data
With portfast

2. When should CDP be enabled?
By an ARP access list that defines the permitted bindings
Interim solution - uses same hardware as WEP - but uses TKIP encryption
Forces the router to wait for a period of time before attempting overthrow
Only for trusted Cisco gear - especially phones

3. How does ISL handle COS?
Only on ports that have same static VLANs or trunking. It also modifies parameters of the channel if one of the ports is modified
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
Effectively stops STP on filtered ports
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server

4. How does a Cisco IP phone connect upstream?
Via an 802.1Q trunk or a single VLAN access port
Used when there are 1 or more VLANs mapped to a single STP instance
When a wireless station transmits a frame - the receiving one must send an ack
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client

5. What is an untrusted port under dhcp snooping?
Yes
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
Switching Database Manager - configures and prunes TCAM partitions
TCAM

6. How does HSRP election work?
Bridge priority and MAC
Every switch and router in a network must be configured with appropriate QoS features and policies
Distribution layer
Based on priority (0-255). Default is 100. Highest IP is tie breaker

7. What does the ip option do when checking ARP replies

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8. What are the RSTP port roles?
An ac adaptor that plugs into a wall outlet.
Root - designated - alternate - and backup
Based on priority (0-255). Default is 100. Highest IP is tie breaker
Only a single host connects . If one BDPU is received - it is no longer an edge port

9. What feedback mechanism does wireless use?
FIB
When a wireless station transmits a frame - the receiving one must send an ack
Will trunk if asked
Per VLAN

10. RSTP discarding state
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
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
Incoming frames are dropped (combination of disabled - blocking - and listening)
1 IP subnet

11. What is a service set?
A group of wireless devices that share a common SSID
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information
Port stays up - packets from violating MACs dropped - no logging

12. What is DSCP codepoint AF11(10)?
VTP server for domain null with no password or secure mode
Every switch and router in a network must be configured with appropriate QoS features and policies
Priority (class 1)
134 bits - consisting of source and destination addresses and protocol information from the packet or frame

13. What are the two etherchannel negotiation protocols?
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root
PAgP (Cisco proprietary) and LACP (standards-based)
Trusted or untrusted

14. What are the 5 steps a LAP uses to establish communication with a WLC?
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
3 seconds. Holdtime =3 hellos + 1
The configureable UDLD interval must be less than max age plus two intervals of forward delay
2 - one for control messages and one for data

15. What happens when switches receive a configuration BDPU?
They disguise the origin of an attack
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
1-1005 (1 and 1002-1005 are reserved)
Gateway load balancing protocol - cisco proprietary

16. For QoS - switch uplinks should always be considered as ____ _____?
Show standby
As a VLAN access map
Regions and instances
Trusted ports

17. 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
3 seconds. Holdtime =3 hellos + 1
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
One that can be detected on a switch interface (ie. Up/down)

18. What does the epoch number indicate when looking at cef entries?
Flash (class 3)
802.1x with EAP over LAN (EAPOL)
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves
The number of times the CEF table has bee flushed and regenerated as a whole

19. What duplex setting does 802.11 use and why?
Another router must have a higher HSRP priority and have preemt set up
No
Half because transmitting and receiving stations use the same frequency
Either desirable or auto mode

20. How does IPT behave when the voice VLAN is in vlan-id mode?
FIB
802.1D
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added

21. What are the 4 steps in DHCP negotiation?
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
On ports where you never expect to find a root bridge for a VLAN
MST attributes must be manually entereed on each switch in the region. They don' t propagate like VTP.
1 second. Backup routers can learn the interval from the master

22. What are the 5 STP port roles?
Those that connect to other switches
Root - designated - blocking - alternate - forwarding (host)
Between any type of interface as long as the interface can have an L3 address assigned
Only when a nonedge port transitions to forwarding

23. What does Root Guard do?
Port with best root path cost
Bridge priority and MAC
Connects with SONET or SDH
Controls where candidate root bridges can be connected and found on a network

24. What are the 3 trunk switchport modes?
Multicast to 01-80-c2-00-00-00
Trunk - dynamic auto - dynamic desireable (default)
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added
Automatically using DTP and CDP

25. How does every HSRP config command begin?
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL
Switch(config-if)# standby xx where x= group number
Every switch and router in a network must be configured with appropriate QoS features and policies
RADIUS

26. How is the IPT 802.1 trunk negotiated?
Automatically using DTP and CDP
Untrusted
Only when a nonedge port transitions to forwarding
5 classes with 3 drop precedences

27. How does a DAI enabled switch gather trusted ARP info?
Route processor redundancy - redundant sup is partially booted and initialized and must reload module in the switch and init all sup functions
From the DHCP snooping database or from static entries
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated

28. How does packet forwarding work
Checks the source MAC in the header against the sender MAC in the ARP reply
0-255 (lower is better)
L2
Arp for local subnet - if on different subnet - will arp for dgw

29. How does IPT behave when the voice VLAN is in dot1p mode?
0-65535 (def 32768) lower=better
Checks the destination MAC in the header against the target MAC in the ARP reply
Collision domain
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p

30. What are the 5 STP states?
The campus network's backbone
1 to 64
Disabled - blocking - listening - learning - forwarding
Time between BDPUs sent by root bridge. Default of 2 seconds

31. What is the range of PAgP channel group numbers?
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
Differentiated services
Only for the offending VLAN on the port
1 to 64

32. What are the 4 steps to extend QoS trust?
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
1-lowest root bridge ID - 2-lowest root path cost - 3-lowest bridgeID - 4-lowest port ID
1- enable qos - 2-define qos parameters to be trusted - 3-make trust conditional - 4-instruct IP phone how to extnd boundary
A client can roam to any WLC as long as it stays in a mobility group

33. How do you prevent switch spoofing?
Only for trusted Cisco gear - especially phones
By configuring every switch port to have an expected and controlled behavior
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks

34. 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
Priority (class 1)
Option 43
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge

35. What functions does a WLC perform?
10-15%
Compatible with 802.11b - up to 54Mbps in 12 data rates - 3 channels - 2.4Ghz
Via an 802.1Q trunk or a single VLAN access port
Control functions

36. What is DAI?
Dynamic arp inspection
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
Aggregation - high L3 throughput - security and policy based connectivity functions through access lists and packet filters - QoS - scalable high-speed links
1500B

37. How is RSTP synchronization accomplished?
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
Port with best root path cost
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root

38. what I s distributed CEF (dCEF)?
After forwarding delay - port can learn new MAC addresses
Only for the offending VLAN on the port
CEF is distributed completely among multiple L3 forwarding engines.
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config

39. What is step 1 of enabling IP source guard?
The DCF interframe space- the random backoff time before a wireless set can transmit
On by default
A MAC is seen on a different port
Configure and enable DHCP snooping

40. How does DSCP handle IP precedence?
Dynamic arp inspection
When each AP stands alone within the larger network.
5 classes with 3 drop precedences
The configureable UDLD interval must be less than max age plus two intervals of forward delay

41. WPA2 encryption
By using a trunk link
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN
Between any type of interface as long as the interface can have an L3 address assigned
Needs hardware upgrade over WEP - uses AES encryption

42. What is DSCP codepoint AF41(34)?
Sends special layer 2 UDLD frames and expects an echo. Both ends must be configured for UDLD
63 kbps
900 MHz - 2.4Ghz - and 5-6GHz
Flash override (class 4)

43. What is the STP hello timer?
As a VLAN access map
Matching SSID - compatible data rate - authentication credentials
Time between BDPUs sent by root bridge. Default of 2 seconds
That they aren't using the same frequencies.

44. How far chould a VLAN extend?
Up to 4 can be used in a group. Called active virtual forwarders (AVF)
Distribution layer
As a VLAN access map
2 strand MMF with MT-RJ or SC connectors

45. How does Root Guard work?

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46. Where is the QoS trust boundary usually configured on an IP phone?
Promiscuous and host
The port will operate under 802.1D rules. If they are received on the same port - it will run 802.1D until the migration delay expires
MST attributes must be manually entereed on each switch in the region. They don' t propagate like VTP.
Usually QoS from VOIP but not PC dataa

47. What does MSTP consist of?
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
Regions and instances
A point to point port type but the neighboring device runs traditional 802.1D STP
80% of the user traffic should stay in the VLAN

48. What is a QoS trust boundary?
Packets are discarded due to an ACL or policy action
Each physical interface has a different IP address. All physical interfaces point to a virtual interface called the standby address or VIP
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz

49. What does the RP do?
Best effort delivery - integrated services model - and differentiated services model
A VLAN that spans the entire fabric
FE and GE
Receives the first packet of a traffic flow and routes it

50. Where shoul dmultilayer switches be implemented?
Distribution layer
1-1005 (1 and 1002-1005 are reserved)
Port stays up - packets from violating MACs dropped - no logging
Isl - dot1q - negotiate (default)