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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. How do VRRP routers handle preemption?
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
Discarding - learning - forwarding
Frames that barely exceed 1518B or 1622B due to headers
On by default

2. What are the restrictions for bundling into an Etherchannel?
MAC of the end device
No because they only participate if asked
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings
It is enabled by default on all CEF capable switches

3. What is unique about HSRP group numbers?
The standby becomes active and stays active by default. Preemption can be configured
0000.5e00.01xx
By using a trunk link
They are locally significant on an interface. HSRP1 on one VLAN is different from HSRP1 on another

4. On what scope is DAI enabled?
When a port moves into forwarding or from fowarding or learning to blocking.
Distribution
Roughly 2000
Per VLAN

5. How does IPT behave when the voice VLAN is in dot1p mode?
1-lowest root bridge ID - 2-lowest root path cost - 3-lowest bridgeID - 4-lowest port ID
Used when there are 1 or more VLANs mapped to a single STP instance
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
They disguise the origin of an attack

6. Where is bdpu guard enabled?
All user ports that have portfast enabled
802.11
1 to 64
A VLAN that spans the entire fabric

7. How do IP phones communicate with each other?
Once the CCM gives them the parameters - they use RTP
Root - designated - alternate - and backup
An instance of RSTP running for each VLAN on the switch. Changing from PVST to RPVST+ is disruptive
A private VLAN can be logically associated with a special secondary vlan

8. What is the port number range?
0-255
Will trunk if asked
Incoming frames are dropped (combination of disabled - blocking - and listening)
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz

9. What is the core block?

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10. How many tunnels exist between the LAP and WLC?
By brining up a tunnel between them to carry 802.11 related messages and client data.
802.1D
2 - one for control messages and one for data
Disabled - blocking - listening - learning - forwarding

11. What do you need to determine to use MSTP?
Switch(config-if)# glbp xx where xx = group number
Port with best root path cost on segment
802.1D
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance

12. What does the reload keyword do in HSRP?
Forces the router to wait for a period of time after the switch is reloaded before attempting to overthrow
LACP port priority
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.
MST attributes must be manually entereed on each switch in the region. They don' t propagate like VTP.

13. WEP encryption
One that can be detected on a switch interface (ie. Up/down)
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
Weak key rotation
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p

14. What are the 2 choices for VLANs with IPT?
By sending a gratuitous ARP
26-byte header - 4-byte trailer with CRC
Etherchannel ports have inconsistent config
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)

15. How are errdisable triggers tuned?
Makes use of the DHCP snooping database and static ip source binding entries. If enabled - switch will test addresses
Globally
Only for trusted Cisco gear - especially phones
Automatically by duplex mode in use. Full duplex are point ot point. Half duplex ports use traditional 802.1D convergence is used.

16. How does GLBP work?
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
Using a single WAP to centralize access and control over a group of wireless devices.
On (all ports channel) - auto (channels when asked) - and desirable(actively asks to form a channel)
Routers are assigned to common GLBP group. All routers can be active and can load balance

17. Whan is a 10GE WAN PHY?
Hashing algorithm
Connects with SONET or SDH
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.
By encapsulating each frame in a header and trailer

18. When DHCP snooping is turned on - by default - it considers all ports ______
FE and GE
Hashing algorithm
Route once - switch many
Untrusted

19. What does BDPU filtering do?
16 bits (8b port priority - 8b port 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.
Effectively stops STP on filtered ports
Backbonefast uses RLQ to determine if upstream switches have stable connections to root bridge

20. What is layer 2 roaming?
Multicast to 01-80-c2-00-00-00
If the client maintains the same IP address as it roams between Aps. All must have same VLAN - SSID - and subnet
Only for trusted Cisco gear - especially phones
FE and GE

21. How can you tell if a switch block is too large?
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
Hashing algorithm
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block
Arp for local subnet - if on different subnet - will arp for dgw

22. How does HSRP do MD5 authentication?
The MST instance (MSTI) runs alongside the IST and represents an STP instance
By using a hash of a key string
On ports where you never expect to find a root bridge for a VLAN
2

23. What is the adjacency table?
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
Trunk

24. What pins does FE use?
L2
1/2 and 3/6
Limits the number if dhcp requests on a port
1 IP subnet

25. What does the SP do?
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
Both ends should be on because on modes doesn't send PAgP or LACP packets
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
Between any type of interface as long as the interface can have an L3 address assigned

26. How does the CEF L3 engine operate?

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27. what should you do if you expect a PAgP capable switch at the other end vs. a server or host?
Manually
Configure non-silent submode
2
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.

28. What is a bridge ID made up of?
A key string of up to 8 characters is sent. Default is cisco.
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
Bridge priority and MAC
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack

29. How are frames forwarded across a specific link?
Interim solution - uses same hardware as WEP - but uses TKIP encryption
Access
Hashing algorithm
No shut

30. What is the GLBP group and priority range
FIB
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies
Group (0-1023) priority (1-255 higher better def 100)
An L2 switch can only forward frames best effort unless going across a trunk

31. What happens when switches receive a configuration BDPU?
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
1 per segment
Port stays up - packets from violating MACs dropped - no logging
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)

32. What is the 80/20 rule?
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
80% of the user traffic should stay in the VLAN
FE and GE
Another router must have a higher HSRP priority and have preemt set up

33. What is latency?
Trunk
The total delay from start to finish
The configureable UDLD interval must be less than max age plus two intervals of forward delay
It is enabled by default on all CEF capable switches

34. What is the STP hello timer?
4
Time between BDPUs sent by root bridge. Default of 2 seconds
By an ARP access list that defines the permitted bindings
Change in trunk encap

35. Automatically configure STP timers
Local only
Those that connect to other switches
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
Use the spanning-tree root macro

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

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37. What are the 5 STP states?
Critical...used most often for IPT
Port is forced to never authorize any connected client
Disabled - blocking - listening - learning - forwarding
Transmits keystrokes from phone and commands from CCM

38. 802.11g
Compatible with 802.11b - up to 54Mbps in 12 data rates - 3 channels - 2.4Ghz
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
A single broadcast domain
Up to 4 can be used in a group. Called active virtual forwarders (AVF)

39. What is UDLD aggressive mode?

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40. What are the caveats for HSRP port tracking?
Virtual Router Redundancy Protocol - pretty much the same as HSRP
Only for trusted Cisco gear - especially phones
Another router must have a higher HSRP priority and have preemt set up
Dynamic WEP keys that change periodically

41. What is 802.1x force-authorized?
Limits the number if dhcp requests on a port
Another router must have a higher HSRP priority and have preemt set up
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
The port is forced to always authorize any connected client with no authentication necessary (default)

42. What is a microcell?
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
When the size of a cell is intentionally reduced
Flash override (class 4)
The TOS field in the header is used. 2 methods 3 bits or 6 bits

43. What categories can ports be in with dhcp snooping enabled?
All nondesignated ports - but ok for all ports
802.1x with EAP over LAN (EAPOL)
Trusted or untrusted
Port

44. How does backbonefast determine whether alternative paths exist?
Access
Distributed coordinion function - the use of timers to prevent wireless collisions
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies
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

45. What is an autonomous mode AP?
When each AP stands alone within the larger network.
Between interfaces that are assigned to L2 VLANs or L2 trunks
Variation in delay
Makes use of the DHCP snooping database and static ip source binding entries. If enabled - switch will test addresses

46. What is the default VTP state?
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client
VTP server for domain null with no password or secure mode
Hosts associated with a secondary VLAN can communicate with ports on the primary but not with another secondary VLAN
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz

47. What must be supported for port-based security to occur?
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server
802.1x with EAP over LAN (EAPOL)
Real-time Transport Protocol
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each

48. What is an IBSS?
The wireless clients communicate directly with no other means of connectivity such as a WAP
Arp for local subnet - if on different subnet - will arp for dgw
A key string of up to 8 characters is sent. Default is cisco.
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added

49. What criteria are used to size a switch block?
Configure the timer on the AVG and let it propagate
An L2 switch can only forward frames best effort unless going across a trunk
0-255
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains

50. How does an L2 switch do QOS?
An L2 switch can only forward frames best effort unless going across a trunk
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
Almost eliminates listening and learning states for single hosts on an access link
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