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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. How many potential links can LACP define?
16 - of which up to 8 are active. The others are in standby
2 seconds
Globally
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports

2. What are the RSTP port states?
Usually QoS from VOIP but not PC dataa
Critical...used most often for IPT
Only a single host connects . If one BDPU is received - it is no longer an edge port
Discarding - learning - forwarding

3. How does 802.1q handle COS?
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
Globally or per-port
When each AP stands alone within the larger network.
134 bits - consisting of source and destination addresses and protocol information from the packet or frame

4. What address does HSRP send hello packets to?
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance
By default weight is 100. Can be made dynamic per interface
Switch(config-if)# glbp xx where xx = group number
224.0.0.2 (all routers)

5. How does PAgP form etherchannels?
Data and voice over native vlan - no QOS but still uses 802.1p trunk
Gets assistance from other NSF-aware neighbors. NSF features need to be built into the routing protocols on router needing and providing assistance
Root
Only on ports that have same static VLANs or trunking. It also modifies parameters of the channel if one of the ports is modified

6. How is DHCP snooping enabled (scope)?
Route once - switch many
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
Used to switch packets destined for the null interface
Globally

7. What does Loop Guard do?
1/2 and 3/6
Interim solution - uses same hardware as WEP - but uses TKIP encryption
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks
When a port moves into forwarding or from fowarding or learning to blocking.

8. can root guard and udld be used together?
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
Yes

9. How many designated ports are there?
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
1 per segment
Time between BDPUs sent by root bridge. Default of 2 seconds
Full duplex

10. How much BW does a voip connection use?
12 kbps with headers and compression
1/2 and 3/6
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
Configuration and TCN

11. How does HSRP gateway addressing work
Roughly 50%
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings
Each physical interface has a different IP address. All physical interfaces point to a virtual interface called the standby address or VIP
By an ARP access list that defines the permitted bindings

12. What is arp throttling?
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
Determines when the AVG will stop using the old VMAC in ARP replies
Only when a nonedge port transitions to forwarding
5 classes with 3 drop precedences

13. What types of authentication does HSRP allow?
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
Using a mobility exchange message
Plain text or md5
Manages addition - deletion and renaming VLANs across the network

14. When should CDP be enabled?
0-255
Multicast to 01-80-c2-00-00-00
Show standby
Only for trusted Cisco gear - especially phones

15. What does UDLD do?
5 classes with 3 drop precedences
Trunk - dynamic auto - dynamic desireable (default)
Real-time Transport Protocol
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)

16. What are the 2 choices for VLANs with IPT?
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
They must be carried over a voice VLAN (VVID) or over a regular data VLAN (ie. The native VLAN or the PVID)
PAgP (Cisco proprietary) and LACP (standards-based)
An ac adaptor that plugs into a wall outlet.

17. How are VACLs applied
To a VLAN and not to a VLAN interface (SVI)
2 seconds
Globally
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding

18. Which 4 things must be agreeable to trunk?
1- trunking mode - 2-trunk encapsulation - 3-native VLAN - 4-allowed VLAN
Transmits keystrokes from phone and commands from CCM
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)

19. What are the 2 UDLD modes?
Normal and aggressive
224.0.0.2 (all routers)
Weak key rotation
To the virtual port-channel interface

20. What types of link can an etherchannel be?
Access or trunk
Round robin - weighted - or host-dependent
Only on ports that have same static VLANs or trunking. It also modifies parameters of the channel if one of the ports is modified
Distribution layer

21. How is UDLD configured?
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port
134 bits
Per-port or globally for all fiber-optic ports. Can be enabled globally - but will only affect fiber ports
Used to switch packets that can't be forwarded normallly due to an encapsulation failure - unresolved address - unsupported protocol - etc.

22. What is topology-basec caching?
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
Interim solution - uses same hardware as WEP - but uses TKIP encryption
A router keeps a routing table and an ARP table. The FIB combines them for every next-hop entry
Normal and aggressive

23. What does port-security protect do?
It's a router that maintains routes (static or dynamic) - and populates the FIB
An instance of RSTP running for each VLAN on the switch. Changing from PVST to RPVST+ is disruptive
Port stays up - packets from violating MACs dropped - no logging
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p

24. For QoS - switch uplinks should always be considered as ____ _____?
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.
Completed dhcp bindings - mac addresses - IP addresses - etc.
Trusted ports
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance

25. What is the STP forwarding state?
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
FIB
Yes
Needs hardware upgrade over WEP - uses AES encryption

26. What is the STP learning state?
0-255 (lower is better)
After forwarding delay - port can learn new MAC addresses
Local only
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block

27. What duplex setting does 802.11 use and why?
1-(opt) set system priority - 2-select interface(s) - 3-assign the protocol - 4-set the mode - 5-(opt) set the port priority
Half because transmitting and receiving stations use the same frequency
2 strand MMF with MT-RJ or SC connectors
After forwarding delay - port can learn new MAC addresses

28. What does the static keyword do when applying an arp ACL?
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based
Prevents the dhcp binding DB from being checked.
Disabled - init - listen - speak - standby - active
No because they only participate if asked

29. How is RSTP synchronization accomplished?
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
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root
Automatically using DTP and CDP
1 to 64

30. How does HSRP election work?
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
Group (0-255) - priority (1-254 254 is highest - 100 default)
Based on priority (0-255). Default is 100. Highest IP is tie breaker

31. unknown unicast flooding
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.
By short-circuiting the max age timer
Weak key rotation
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each

32. What does the rewrite engine do?
Use sh interface on the interface and look for error counts > 10
Real-time Transport Protocol
134 bits
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information

33. What must be supported for port-based security to occur?
By default weight is 100. Can be made dynamic per interface
Trusted or untrusted
BGP - EIGRP - OSPF - and IS-IS.
802.1x with EAP over LAN (EAPOL)

34. How does every HSRP config command begin?
Matching SSID - compatible data rate - authentication credentials
On ports where you never expect to find a root bridge for a VLAN
By short-circuiting the max age timer
Switch(config-if)# standby xx where x= group number

35. How should the switch port to which a LAP be configured?
0000.0c07.acxx where xx is the group number as a 2-digit hex value
As a VLAN access map
Makes use of the DHCP snooping database and static ip source binding entries. If enabled - switch will test addresses
Access

36. How do VRRP routers handle preemption?
Reboots and searches for a new WLC
Used to switch packets that can't be forwarded normallly due to an encapsulation failure - unresolved address - unsupported protocol - etc.
On by default
Group (0-1023) priority (1-255 higher better def 100)

37. What is 802.1x auto?
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block
The port uses 802.1x exchange to move from unauthorized to authorized. Requires app on client
With the skinny protocol
Root

38. Define VRRP
Virtual Router Redundancy Protocol - pretty much the same as HSRP
Turn on port security
By using an Ether-IP tunnel
The distribution layer should have only L3 links

39. What criteria are used to size a switch block?
One that can be detected on a switch interface (ie. Up/down)
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server
Traffic types and patterns - amount of L3 switching cap. At dist. Layer - # users at access layer - geography - size of spanning tree domains
Differentiated services

40. What is a microcell?
Untrusted
Edge - root - and point to point
Must be same type - speed - VLAN(s) - native vlan - pass the same set of vlans -duplex - and spanning tree settings
When the size of a cell is intentionally reduced

41. What is the PVLAN host mode?
Silent
Src-ip - dst-ip - src-dst-ip - src-mac - dst-mac - src-dst-mac - src-port - dst-port - src-dst-port
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
Routers at the distribution layer become the bottlenecks or broadcast or multicast traffic slows the switches in the switch block

42. What functions does a WLC perform?
Checks the destination MAC in the header against the target MAC in the ARP reply
By using an Ether-IP tunnel
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS
Control functions

43. What is a service set?
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
Root - designated - blocking - alternate - forwarding (host)
A group of wireless devices that share a common SSID
No shut

44. What 2 tunnelling mechanisms do the LAP and WLC use to communicate?
1- enable qos - 2-define qos parameters to be trusted - 3-make trust conditional - 4-instruct IP phone how to extnd boundary
1-65535 (def 32768) lower priority - higher probability
LWAPP (Cisco proprietary) and CAP-WAP (standards based)
Packets are discarded due to an ACL or policy action

45. What are the 3 ways GLBP load-balances?
Both ends should be on because on modes doesn't send PAgP or LACP packets
A VLAN that spans the entire fabric
Round robin - weighted - or host-dependent
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset

46. What is the default 10mbps Enet duplex?
Distribution layer
Half-duplex
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
Real-time Transport Protocol

47. What are the 5 steps to manualy configure STP?
The DCF interframe space- the random backoff time before a wireless set can transmit
The standby becomes active and stays active by default. Preemption can be configured
CEF is distributed across multiple L3 forwarding engines - typically on Catalyst 6500 line cards each having only a subset
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

48. What method of QOS does voice traffic use most frequently?
Differentiated services
Multicast to 01-80-c2-00-00-00
By encapsulating each frame in a header and trailer
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack

49. What does BDPU filtering do?
By name - config revision - and instance to vlan mapping table
No shut
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
Effectively stops STP on filtered ports

50. What is errdisable dtp-flap?
On the left as you face the connector
Data and voice over native vlan - no QOS but still uses 802.1p trunk
224.0.0.2 (all routers)
Change in trunk encap