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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 is a baby giant frame?
When a client roams between Aps in different subnets
0007.b4xx.xxyy where xx.xx is six 0 bits followed by a 10-bit GLBP group numberr. Yyyy is the virtual forwarder number
The TOS field in the header is used. 2 methods 3 bits or 6 bits
Frames that barely exceed 1518B or 1622B due to headers

2. How many designated ports are there?
1 per segment
Flash override (class 4)
No
Can send and receive BDPUs

3. How do you prevent VLAN hopping?
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
Differentiated services code point
Round robin - weighted - or host-dependent
Completed dhcp bindings - mac addresses - IP addresses - etc.

4. RSTP uses which standard?
802.1w
Using digital certificates
Root
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string

5. How does HSRP port tracking work?

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6. For QoS - switch uplinks should always be considered as ____ _____?
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
Distribution layer
Roughly 50%
Trusted ports

7. How is the IPT 802.1 trunk negotiated?
Admin down
Automatically using DTP and CDP
Based on priority (0-255). Default is 100. Highest IP is tie breaker
Auto mode

8. How does packet forwarding work
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
Arp for local subnet - if on different subnet - will arp for dgw
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode
Disabled - init - listen - speak - standby - active

9. What is a wall wart?
The switch checks the MAC and IP reported in the reply against trusted values. If they don't match - it is dropped and logged
1/2 and 3/6
Only the standby monitors the hello messages from the active router
An ac adaptor that plugs into a wall outlet.

10. What does MSTP do?
Incoming frames are dropped (combination of disabled - blocking - and listening)
Used when there are 1 or more VLANs mapped to a single STP instance
The station must wait until the frame in progress has completed - then wait a random amount of time before transmitting
Distribution layer

11. What is UDLD aggressive mode?

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12. where does L2 switching occur?
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL
134 bits - consisting of source and destination addresses and protocol information from the packet or frame
Between interfaces that are assigned to L2 VLANs or L2 trunks
Yes

13. How does Root Guard work?

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14. How are GLBP timers used?
Each peer sends and receives hellos. Def hello is 3 sec - def hold is 10 sec
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
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
With portfast

15. What is the size of a TCAM value?
The distribution layer should have only L3 links
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
134 bits - consisting of source and destination addresses and protocol information from the packet or frame
By name - config revision - and instance to vlan mapping table

16. How is root port decided upon?
Disabled - blocking - listening - learning - forwarding
Lowest cumulative cost to root
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy
Only for the offending VLAN on the port

17. What is the STP Max Age timer?
The time interval that a switch stores a DBPU before discarding it. Default 20 seconds
Globally
A single broadcast domain
0-255 (lower is better)

18. What does the static keyword do when applying an arp ACL?
A VLAN that spans the entire fabric
Trusted or untrusted
Packets are discarded due to an ACL or policy action
Prevents the dhcp binding DB from being checked.

19. How can BDPU Guard be configured?
Routers are assigned to common GLBP group. All routers can be active and can load balance
Globally or per-port
A single broadcast domain
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

20. What does the rewrite engine do?
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information
Automatically using DTP and CDP
Hold time is 3xhello. A skew time of 256ms-routerpriority)/256ms is added
If the switch or the powered device doesn't suport power class discovery

21. How does 802.3af do power discovery?
802.1x with EAP over LAN (EAPOL)
Sends a voltage across the receive pairs to detect a 25k ohm resistance
1- enable qos - 2-define qos parameters to be trusted - 3-make trust conditional - 4-instruct IP phone how to extnd boundary
Cisco recommends only on the root bridge

22. Where is root guard enabled?

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23. Define VRRP
When the AP uplinks to an Ethernet network.
Virtual Router Redundancy Protocol - pretty much the same as HSRP
The port is forced to always authorize any connected client with no authentication necessary (default)
If any BDUP is received on a port - it puts the port into the errdisable state

24. How is UDLD configured?
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports
Distribution layer
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
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

25. What is the cost of a 100Mbps link?
Interim solution - uses same hardware as WEP - but uses TKIP encryption
19
Hosts within a secondary can communicate with each other and with the primary - but not with another secondary vlan
Dynamic WEP keys that change periodically

26. Which fiber is the receive?
Any dhcp reply coming from an untrusted port is discarded and the offending port is put in errdisable
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
Between any type of interface as long as the interface can have an L3 address assigned
On the left as you face the connector

27. How often are VRRP advertisements sent?
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
Because each frame is checked
Edge - root - and point to point
1 second. Backup routers can learn the interval from the master

28. What pins does FE use?
With the skinny protocol
Port with best root path cost on segment
By using a trunk link
1/2 and 3/6

29. What is arp throttling?
A group of wireless devices that share a common SSID
Used to switch packets that can't be forwarded normallly due to an encapsulation failure - unresolved address - unsupported protocol - etc.
Checks the destination MAC in the header against the target MAC in the ARP reply
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. What is layer 3 roaming?
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port
When a client roams between Aps in different subnets
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings
2

31. What does DTP do?
By default weight is 100. Can be made dynamic per interface
Variation in delay
Automatically negotiates a common trunk mode between switches
Globally or per-port

32. What 2 tunnelling mechanisms do the LAP and WLC use to communicate?
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac
Distribution layer
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy
LWAPP (Cisco proprietary) and CAP-WAP (standards based)

33. What is accelerated CEF (aCEF)?
A single broadcast domain
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
CEF is distributed completely among multiple L3 forwarding engines.
On the left as you face the connector

34. What is a direct topology change?
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
One that can be detected on a switch interface (ie. Up/down)
An ac adaptor that plugs into a wall outlet.
Trunk

35. What is the GLBP AVG?
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
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
2-8 FE - GE - or 10GE are bundled.
10-15%

36. What is the SDM?
Switching Database Manager - configures and prunes TCAM partitions
The time that a port spends in both listening and learning states . Default 15 seconds
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
From the DHCP snooping database or from static entries

37. What is step 1 of enabling IP source guard?
Port that connects to another switch and becomes a designated port
A packet can't be switched in hardware with the FIB and must go to the L3 engine
Yes
Configure and enable DHCP snooping

38. How does HSRP do MD5 authentication?
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged
134 bits
By using a hash of a key string
802.11

39. What is a topology change?
300 sec by default
When a port moves into forwarding or from fowarding or learning to blocking.
L2
The master router can share the VIP

40. How does backbonefast determine whether alternative paths exist?
Edge - root - and point to point
63 kbps
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
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

41. How many 802.3af power classes are there?
5 (0-4 with 4 being the highest)
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.
Use the spanning-tree root macro
Configure and enable DHCP snooping

42. What is RPR?
If a proposal is received - the recipient isolates - all nonedge ports blocked until proposal sent causing neighbors to synch - which propagates out in waves
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
Route processor redundancy - redundant sup is partially booted and initialized and must reload module in the switch and init all sup functions
Forces the router to wait for a period of time before attempting overthrow

43. 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
No
A MAC is seen on a different port
A private VLAN can be logically associated with a special secondary vlan

44. What is a null adjacency?
By configuring every switch port to have an expected and controlled behavior
Used to switch packets destined for the null interface
Auto mode
2

45. What does port-security protect do?
All fiber-optic links between switches (must be enabled on both ends)
The ASIC
Port stays up - packets from violating MACs dropped - no logging
300 sec by default

46. Can loop guard and udld be used together?
Yes
Determines when the AVG will stop using the old VMAC in ARP replies
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
Configure non-silent submode

47. How do VRRP routers handle preemption?
On by default
5 classes with 3 drop precedences
Sends a voltage across the receive pairs to detect a 25k ohm resistance
Manually

48. What happens if both 802.1D and RSTP BDPUs are received?
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
2 seconds (def)
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.
Manually

49. What 2 conditions does IP source guard check for?
Source IP and MAC must match those addresses learned by DHCP snooping or a static entry
BGP - EIGRP - OSPF - and IS-IS.
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
All ARP packets that arrive on untrusted ports are inspected.

50. What is the default MTU?
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
Use the spanning-tree root macro
Used when ACLs specify port ranges...used by TCAM
1500B