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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 2 choices for VLANs with IPT?
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
By brining up a tunnel between them to carry 802.11 related messages and client data.
Root - designated - blocking - alternate - forwarding (host)

2. What is portfast?
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.
Root - designated - blocking - alternate - forwarding (host)
That they aren't using the same frequencies.
Almost eliminates listening and learning states for single hosts on an access link

3. What is latency?
Checks the destination MAC in the header against the target MAC in the ARP reply
The total delay from start to finish
Option 43
Switch(config-if)# standby xx where x= group number

4. Define GLBP
Yes to both
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
Gateway load balancing protocol - cisco proprietary

5. What is Per VLAN STP (PVST)?
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
Collision domain

6. How does IPT behave when the voice VLAN is in vlan-id mode?
CEF is distributed completely among multiple L3 forwarding engines.
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
Almost eliminates listening and learning states for single hosts on an access link

7. What is jitter?
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports
If a unidirectional link is detected - the switch doesn't try to reestablish the link. ULD msgs are sent once/sec for 8 seconds - then the port is err-disabled
Variation in delay
Needs hardware upgrade over WEP - uses AES encryption

8. How does a LAP and a WLC authenticate between each other?
On ports where you never expect to find a root bridge for a VLAN
On all switches in network to enable RLQ request and reply
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
Using digital certificates

9. If you want IP source guard to detect spoofed MAC addresses - what must you do?
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
Limits the number if dhcp requests on a port
Receives the first packet of a traffic flow and routes it
Turn on port security

10. How does loop guard block ports?
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
Only for the offending VLAN on the port
Only a single host connects . If one BDPU is received - it is no longer an edge port
Trusted ports

11. What is layer 3 roaming?
224.0.0.2 (all routers)
The time that a port spends in both listening and learning states . Default 15 seconds
When a client roams between Aps in different subnets
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP

12. Where is loop guard enabled?
All nondesignated ports - but ok for all ports
63 kbps
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
Admin down

13. How are GLBP timers used?
On the left as you face the connector
Switches make an effort to move packets as quickly as possible
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
When a client roams between Aps in different subnets

14. 802.11b
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
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
Aggregation - high L3 throughput - security and policy based connectivity functions through access lists and packet filters - QoS - scalable high-speed links
Port with best root path cost

15. What is the STP listening state?
Globally or per-port
2
Can send and receive BDPUs
By creating a static IP binding

16. How does an LAP bind with a WLC?
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
By brining up a tunnel between them to carry 802.11 related messages and client data.

17. What are the VRRP group and priority numbers?
Group (0-255) - priority (1-254 254 is highest - 100 default)
Yes
Both layer 2 switching and IVR
Access or trunk

18. What is integrated services model QOS?
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
On the left as you face the connector
Globally
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.

19. How does HSRP election work?
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
Roughly 50%
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port
Based on priority (0-255). Default is 100. Highest IP is tie breaker

20. What are the 5 steps a LAP uses to establish communication with a WLC?
Local only
Globally
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
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config

21. What is the STP blocking state?
Can hear only BDPUs
A client can roam to any WLC as long as it stays in a mobility group
Sends a voltage across the receive pairs to detect a 25k ohm resistance
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP

22. How often are BDPUs sent?
Can send and receive BDPUs
2 seconds (def)
To the virtual port-channel interface
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN

23. What are the three basic types of QOS?
Automatically using DTP and CDP
1-lowest root bridge ID - 2-lowest root path cost - 3-lowest bridgeID - 4-lowest port ID
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added
Best effort delivery - integrated services model - and differentiated services model

24. What is the STP learning state?
After forwarding delay - port can learn new MAC addresses
Globally or per-port
The active router. All other routers are in backup state
Roughly 50%

25. How can you tell if a switch block is too large?
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
Stateful switchover - redundant sup is fully booted and init'd. Both start and run config are synched as is L2 information - and switchinterfaces.
Isolated and community
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block

26. How are errdisable triggers tuned?
An instance of RSTP running for each VLAN on the switch. Changing from PVST to RPVST+ is disruptive
Only a single host connects . If one BDPU is received - it is no longer an edge port
Via an 802.1Q trunk or a single VLAN access port
Globally

27. What is the SDM?
With portfast
All L2 connectivity should be contained within the access layer.
Switching Database Manager - configures and prunes TCAM partitions
LWAPP (Cisco proprietary) and CAP-WAP (standards based)

28. How does the standby handle ARP issues after it becomes active?
The number of times the CEF table has bee flushed and regenerated as a whole
Embeds the tag within the frame
VTP server for domain null with no password or secure mode
By sending a gratuitous ARP

29. What is arp throttling?
Completed dhcp bindings - mac addresses - IP addresses - etc.
Up to 4 can be used in a group. Called active virtual forwarders (AVF)
Almost eliminates listening and learning states for single hosts on an access link
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

30. How should the switch port to which a WLC be configured?
Data and voice over native vlan no QOS and no 802.1p trunk
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
Trunk

31. What is a proxy arp?

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32. What are the 3 trunk encap modes?
Isl - dot1q - negotiate (default)
900 MHz - 2.4Ghz - and 5-6GHz
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server

33. What is a topology change?
On by default
SC fiber or RJ-45
When a port moves into forwarding or from fowarding or learning to blocking.
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port

34. What is the cost of a 100Mbps link?
19
Root - designated - alternate - and backup
Only the standby monitors the hello messages from the active router
0000.5e00.01xx

35. What is the default mode of load balancing?
Port with best root path cost
Group (0-1023) priority (1-255 higher better def 100)
SC fiber or RJ-45
Src-dst-ip

36. What is 802.1x force-authorized?
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
Only for trusted Cisco gear - especially phones
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
The port is forced to always authorize any connected client with no authentication necessary (default)

37. Automatically configure STP timers
Two distribution switches that aggregate one or more access switches
Use the spanning-tree root macro
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
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

38. How do you prevent VLAN hopping?
By using an Ether-IP tunnel
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
Embeds the tag within the frame
Each network device handles packets individually with no advance reservations

39. What is a discard adjacency?
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
Packets are discarded due to an ACL or policy action
Port with best root path cost on segment
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets

40. If the WLC connects to an Etherchannel - how should the channel be configured and why?

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41. What does MSTP consist of?
Regions and instances
3 seconds. Holdtime =3 hellos + 1
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves
Forces the router to wait for a period of time after the switch is reloaded before attempting to overthrow

42. How should the switch port to which an autonomous AP be configured?
To a VLAN and not to a VLAN interface (SVI)
Trunk
No
A host port goes up or down

43. What is a BSS?
2
Using a single WAP to centralize access and control over a group of wireless devices.
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
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.

44. can root guard and udld be used together?
Sends a voltage across the receive pairs to detect a 25k ohm resistance
Yes
Automatically by duplex mode in use. Full duplex are point ot point. Half duplex ports use traditional 802.1D convergence is used.
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable

45. How doed backbonefast work?
Usually QoS from VOIP but not PC dataa
By short-circuiting the max age timer
Will trunk if asked
Can send and receive BDPUs

46. What is an IST instance?
Sends a test tone on the transmit pair. If a device is detected - CDP is used to narrow down the power class.
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy
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.
Plain text or md5

47. What is the GLBP AVG?
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
Sends a test tone on the transmit pair. If a device is detected - CDP is used to narrow down the power class.
It is enabled by default on all CEF capable switches
Each frame transmits its expected duration time

48. How does IPT behave when the voice VLAN is in untagged mode?
Data and voice over native vlan - no QOS but still uses 802.1p trunk
When a client roams between Aps in different subnets
Used to switch packets destined for the null interface
Manually

49. What is a bridge ID made up of?
Trunk - dynamic auto - dynamic desireable (default)
Bridge priority and MAC
802.1x with EAP over LAN (EAPOL)
Should be used on access switches - can't be used on root - keeps enabled switch from becoming root by raising priority of switch and all ports - making them undesirable

50. How far chould a VLAN extend?
Discarding - learning - forwarding
Distribution layer
Only when a nonedge port transitions to forwarding
MAC of the end device