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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. Which ports should you consider trusted for DAI?
The MST instance (MSTI) runs alongside the IST and represents an STP instance
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
Those that connect to other switches
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable

2. What is Per VLAN STP (PVST)?
Local only
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
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
Arp for local subnet - if on different subnet - will arp for dgw

3. What is DSCP codepoint AF41(34)?
Each network device handles packets individually with no advance reservations
The port is forced to always authorize any connected client with no authentication necessary (default)
Flash override (class 4)
Globally

4. What does the RP do?
Receives the first packet of a traffic flow and routes it
Etherchannel ports have inconsistent config
The time that a port spends in both listening and learning states . Default 15 seconds
224.0.0.2 (all routers)

5. How does ISL handle COS?
1-(opt) set system priority - 2-select interface(s) - 3-assign the protocol - 4-set the mode - 5-(opt) set the port priority
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
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
FIB

6. How does VRRP do tracking?

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7. What is a proxy arp?

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8. How do you enable CEF?
7 switches from root bridge
Configure and enable DHCP snooping
It is enabled by default on all CEF capable switches
Collision domain

9. What is DSCP?
Between interfaces that are assigned to L2 VLANs or L2 trunks
Differentiated services code point
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
Isl - dot1q - negotiate (default)

10. What if RSTP BDPUs aren't received?
Local only
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
Frames are forwarded
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

11. When a host is connected to a switchport - why aren't frame errors propagated?
Flash override (class 4)
Differentiated services
Because each frame is checked
On all switches in network to enable RLQ request and reply

12. What are the 3 unlicensed frequencies?
900 MHz - 2.4Ghz - and 5-6GHz
The ASIC
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting
An L2 switch can only forward frames best effort unless going across a trunk

13. What is an IBSS?
No
Embeds the tag within the frame
Packets must be sent to the L3 engine for further processing
The wireless clients communicate directly with no other means of connectivity such as a WAP

14. RSTP learning state
Round robin - weighted - or host-dependent
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
Incoming frames dropped - but MACs learned
1-65535 (def 32768) lower priority - higher probability

15. How is the IPT 802.1 trunk negotiated?
Automatically using DTP and CDP
Switch(config-if)# vrrp xx where xx= group number
Port is forced to never authorize any connected client
VTP server for domain null with no password or secure mode

16. What duplex setting does 802.11 use and why?
Half because transmitting and receiving stations use the same frequency
Between any type of interface as long as the interface can have an L3 address assigned
All user ports that have portfast enabled
Half-duplex

17. How does ISL do trunking?
By encapsulating each frame in a header and trailer
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies

18. How often are CAM table entries aged?
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.
300 sec
One that can be detected on a switch interface (ie. Up/down)

19. What does BDPU filtering do?
Effectively stops STP on filtered ports
The port asks the other end to trunk
Two distribution switches that aggregate one or more access switches
Automatically using DTP and CDP

20. Where are security and QoS ACLs stored?
The same as a standby group in HSRP
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
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
TCAM

21. where does L2 switching occur?
By using a hash of a key string
A point to point port type but the neighboring device runs traditional 802.1D STP
Between interfaces that are assigned to L2 VLANs or L2 trunks
TCAM

22. How are VACLs configured?
As a VLAN access map
Port with redundant - but less deisrable connection to a segment. Possibly root candidate
Switches make an effort to move packets as quickly as possible
Can hear only BDPUs

23. How do you configure IP source guard for hosts that don't use DHCP?
Each network device handles packets individually with no advance reservations
By creating a static IP binding
Disabled - init - listen - speak - standby - active
Low cost - high density ports - multiple scalable uplinks - vlans - traffic and protocol filtering and QoS

24. What are the 3 RSTP port types?
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Edge - root - and point to point
If any BDUP is received on a port - it puts the port into the errdisable state
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each

25. What does DTP do?
Automatically negotiates a common trunk mode between switches
A single broadcast domain
Port with redundant - but less deisrable connection to a segment. Possibly root candidate
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server

26. What is the STP Max Age timer?
Used when there are 1 or more VLANs mapped to a single STP instance
The number of times the entry has been updated since the table was generated
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
All ARP packets that arrive on untrusted ports are inspected.

27. How many tunnels exist between the LAP and WLC?
Automatically negotiates a common trunk mode between switches
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)
2 - one for control messages and one for data

28. RSTP alternate port
A point to point port type but the neighboring device runs traditional 802.1D STP
Port with alternative path to root less desirable than root
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block
Reboots and searches for a new WLC

29. What does the skinny protocol do?
Determines when the AVG will stop using the old VMAC in ARP replies
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry
Automatically negotiates a common trunk mode between switches
Transmits keystrokes from phone and commands from CCM

30. What is an SVI?
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
RADIUS
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
Edge - root - and point to point

31. What is the GLBP AVG?
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
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
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port
Usually QoS from VOIP but not PC dataa

32. How is a QoS trust bondary configured?
Between interfaces that are assigned to L2 VLANs or L2 trunks
Every switch and router in a network must be configured with appropriate QoS features and policies
By sending a gratuitous ARP
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings

33. What are the VRRP group and priority numbers?
0000.5e00.01xx
0-65535 (def 32768) lower=better
Group (0-255) - priority (1-254 254 is highest - 100 default)
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.

34. What is RPVST+?
1-1005 (1 and 1002-1005 are reserved)
3 seconds. Holdtime =3 hellos + 1
An instance of RSTP running for each VLAN on the switch. Changing from PVST to RPVST+ is disruptive
Determines when the AVG will stop using the old VMAC in ARP replies

35. How does packet forwarding work
Matching SSID - compatible data rate - authentication credentials
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy
Low cost - high density ports - multiple scalable uplinks - vlans - traffic and protocol filtering and QoS
Arp for local subnet - if on different subnet - will arp for dgw

36. How should the switch port to which a WLC be configured?
Yes
Yes to both
Trunk
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

37. How much overlap should a wireless repeater have?
Via an 802.1Q trunk or a single VLAN access port
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
Roughly 50%

38. How many users should be within a switch block?
Use the spanning-tree root macro
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover
Value - mask - and result (VMR) combinations
Roughly 2000

39. What are the 5 STP states?
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another
Disabled - blocking - listening - learning - forwarding
When a client roams between Aps in different subnets
Checks the destination MAC in the header against the target MAC in the ARP reply

40. How does every VRRP command begin?
Trunk
Access
Switch(config-if)# vrrp xx where xx= group number
BGP - EIGRP - OSPF - and IS-IS.

41. Define VRRP
By name - config revision - and instance to vlan mapping table
Switch(config-if)# glbp xx where xx = group number
Virtual Router Redundancy Protocol - pretty much the same as HSRP
No shut

42. What is the portr ID?
Disabled - blocking - listening - learning - forwarding
16 bits (8b port priority - 8b port number)
When a wireless station transmits a frame - the receiving one must send an ack
Switch(config-if)# vrrp xx where xx= group number

43. Which 4 things must be agreeable to trunk?
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports
Multicasts to 224.0.0.18 (VRRP)
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac

44. What is 802.1x force-unauthorized?
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
Port is forced to never authorize any connected client
L2
A group of wireless devices that share a common SSID

45. How often are HSRP hellos sent?
3 seconds. Holdtime =3 hellos + 1
By using a hash of a key string
Root
A point to point port type but the neighboring device runs traditional 802.1D STP

46. RSTP BPDU structure
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
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server
Yes

47. What does UDLD do?
Virtual Router Redundancy Protocol - pretty much the same as HSRP
Port
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)

48. What is a root link query (RLQ)?
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge
Per VLAN
Needs hardware upgrade over WEP - uses AES encryption
Configure the timer on the AVG and let it propagate

49. How is DHCP snooping enabled (scope)?
No because they only participate if asked
Globally
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover
Dynamic arp inspection

50. What is the cost of a 10Gbps link?
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
2 seconds (def)
0007.b4xx.xxyy where xx.xx is six 0 bits followed by a 10-bit GLBP group numberr. Yyyy is the virtual forwarder number
2