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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 happens if both 802.1D and RSTP BDPUs are received?
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
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
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves
After forwarding delay - port can learn new MAC addresses

2. If a wireless station needs to transmit and another device is transmitting - what happens?
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting
Used when there are 1 or more VLANs mapped to a single STP instance
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
By using a trunk link

3. What are the two private vlan association modes?
Multicast to 01-80-c2-00-00-00
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies
2 seconds (def)
Promiscuous and host

4. What are the 3 trunk switchport modes?
Frames are forwarded
Trunk - dynamic auto - dynamic desireable (default)
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
Port

5. RSTP backup port
Etherchannel ports have inconsistent config
The wireless clients communicate directly with no other means of connectivity such as a WAP
Port with redundant - but less deisrable connection to a segment. Possibly root candidate
Virtual Router Redundancy Protocol - pretty much the same as HSRP

6. How does every VRRP command begin?
Distribution layer
Using a single WAP to centralize access and control over a group of wireless devices.
Switch(config-if)# vrrp xx where xx= group number
Between any type of interface as long as the interface can have an L3 address assigned

7. What is a drop adjacency?

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8. What is 802.1x force-unauthorized?
0007.b4xx.xxyy where xx.xx is six 0 bits followed by a 10-bit GLBP group numberr. Yyyy is the virtual forwarder number
Port is forced to never authorize any connected client
Distribution layer
Once the CCM gives them the parameters - they use RTP

9. How do you disable DTP when you configure both ends of the ISL manually?
Virtual Router Redundancy Protocol - pretty much the same as HSRP
Switchpotrt nonegotiate
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
Only a single host connects . If one BDPU is received - it is no longer an edge port

10. What does MSTP do?
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.
Root
Used when there are 1 or more VLANs mapped to a single STP instance
3 seconds. Holdtime =3 hellos + 1

11. Can two switches in the auto(PAgP) or passive (LACP) mode create a channel? Why?
The DCF interframe space- the random backoff time before a wireless set can transmit
Incoming frames are dropped (combination of disabled - blocking - and listening)
Gateway load balancing protocol - cisco proprietary
No because they only participate if asked

12. How are RSTP point to point ports determined?
The MST instance (MSTI) runs alongside the IST and represents an STP instance
Automatically by duplex mode in use. Full duplex are point ot point. Half duplex ports use traditional 802.1D convergence is used.
When a specific interface is tracked - HSRP reduces it's priority after a specified interval.
3 seconds. Holdtime =3 hellos + 1

13. What is the LACP priority range?
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL
Frames that barely exceed 1518B or 1622B due to headers
1-65535 (def 32768) lower priority - higher probability
Round robin - weighted - or host-dependent

14. What is DSCP?
Normal and aggressive
Collision domain
Differentiated services code point
Port is forced to never authorize any connected client

15. If there are 2 ports with same root cost - how is the tie broken for designated port?
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added
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
1-lowest root bridge ID - 2-lowest root path cost - 3-lowest bridgeID - 4-lowest port ID
When a port moves into forwarding or from fowarding or learning to blocking.

16. How many 802.3af power classes are there?
5 (0-4 with 4 being the highest)
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
It can't
Aggregation - high L3 throughput - security and policy based connectivity functions through access lists and packet filters - QoS - scalable high-speed links

17. What is a bridge ID made up of?
Bridge priority and MAC
No
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
LACP port priority

18. How is root port decided upon?
1- root bridge is elected - 2-the state of eery switch port in the STP domain must be brought from blocking state to the appropriate state
Lowest cumulative cost to root
If the client maintains the same IP address as it roams between Aps. All must have same VLAN - SSID - and subnet
Control functions

19. How is UDLD configured?
RPR - RPR+ - and SSO
Each physical interface has a different IP address. All physical interfaces point to a virtual interface called the standby address or VIP
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports
As a VLAN access map

20. What is errdisable pagp-flap?
Access
The number of times the CEF table has bee flushed and regenerated as a whole
Etherchannel ports have inconsistent config
7 switches from root bridge

21. What is NSF?
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies

22. How does every GLBP command begin
Admin down
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
Switch(config-if)# glbp xx where xx = group number
FIB

23. How is an instance defined?
Source IP and MAC must match those addresses learned by DHCP snooping or a static entry
By name - config revision - and instance to vlan mapping table
It's a router that maintains routes (static or dynamic) - and populates the FIB
Used to switch packets that can't be forwarded normallly due to an encapsulation failure - unresolved address - unsupported protocol - etc.

24. What is the core block?

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25. What is step 1 of enabling IP source guard?
10-15%
Configure and enable DHCP snooping
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
Root

26. What is dynamic auto?
Will trunk if asked
Can hear only BDPUs
802.1w
If any BDUP is received on a port - it puts the port into the errdisable state

27. What criteria are used to size a switch block?
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
Routers are assigned to common GLBP group. All routers can be active and can load balance
An instance of RSTP running for each VLAN on the switch. Changing from PVST to RPVST+ is disruptive
Only on ports that have same static VLANs or trunking. It also modifies parameters of the channel if one of the ports is modified

28. Does VTP pass private VLAN configuration?
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
134 bits - consisting of source and destination addresses and protocol information from the packet or frame
No
Multicasts to 224.0.0.18 (VRRP)

29. How does an L2 switch do QOS?
An L2 switch can only forward frames best effort unless going across a trunk
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
That they aren't using the same frequencies.
Change in trunk encap

30. What are the 5 steps to manualy configure STP?
1-ID link path costs - 2-ID roodt bridge - 3-select root port (1/switch) - 4-select designated port (1/segment) - 5-ID blocking port
FE and GE
By sending a gratuitous ARP
Port is forced to never authorize any connected client

31. What does a LAP do if it loses communication with it's WLC?
Can send and receive BDPUs
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
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
Reboots and searches for a new WLC

32. can root guard and bdpu guard be used together?
Automatically using DTP and CDP
Only for the offending VLAN on the port
No
Configure non-silent submode

33. What are the two etherchannel negotiation protocols?
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port
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
PAgP (Cisco proprietary) and LACP (standards-based)
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS

34. What is the STP Max Age timer?
Globally or per-port
Needs hardware upgrade over WEP - uses AES encryption
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
When each AP stands alone within the larger network.

35. How does HSRP port tracking work?

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36. How many users should be within a switch block?
0000.0c07.acxx where xx is the group number as a 2-digit hex value
Roughly 2000
Option 43
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port

37. How should the switch port to which an autonomous AP be configured?
Trunk
16 bits (8b port priority - 8b port number)
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string
No

38. What is the GLBP redirect timer?
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
After forwarding delay - port can learn new MAC addresses
Determines when the AVG will stop using the old VMAC in ARP replies
802.1x with EAP over LAN (EAPOL)

39. In a converged fabric - which switch(es) send config BDPUs?
Use sh interface on the interface and look for error counts > 10
Promiscuous and host
Only a single host connects . If one BDPU is received - it is no longer an edge port
Root

40. How long are TCAM masks?
Port with alternative path to root less desirable than root
Differentiated services
134 bits
Incoming frames are dropped (combination of disabled - blocking - and listening)

41. What is the GLBP group and priority range
Group (0-255) - priority (1-254 254 is highest - 100 default)
Group (0-1023) priority (1-255 higher better def 100)
On (all ports channel) - auto (channels when asked) - and desirable(actively asks to form a channel)
Real-time functions such as beacons and probes - encryption and interactions with the client at L2

42. What duplex setting does 802.11 use and why?
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
Half because transmitting and receiving stations use the same frequency
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Isolated and community

43. What happens when the topology changes?

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44. What is the 80/20 rule?
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
RPR - RPR+ - and SSO
By short-circuiting the max age timer
80% of the user traffic should stay in the VLAN

45. How is DHCP snooping enabled (scope)?
Globally
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings
Trunk - dynamic auto - dynamic desireable (default)
1/2 and 3/6

46. What is a discard adjacency?
Packets are discarded due to an ACL or policy action
Access or trunk
Between any type of interface as long as the interface can have an L3 address assigned
Each network device handles packets individually with no advance reservations

47. What is the STP hello timer?
When a wireless station transmits a frame - the receiving one must send an ack
Using digital certificates
Time between BDPUs sent by root bridge. Default of 2 seconds
Completed dhcp bindings - mac addresses - IP addresses - etc.

48. What 2 conditions does IP source guard check for?
The distribution layer should have only L3 links
Dynamic arp inspection
Source IP and MAC must match those addresses learned by DHCP snooping or a static entry
Those that connect to other switches

49. What is a LACP priority?
Transmits keystrokes from phone and commands from CCM
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)
The active router. All other routers are in backup state
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology

50. What is UDLD normal mode?
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance
Priority (class 1)