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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. Whan is a 10GE WAN PHY?
The total delay from start to finish
The port asks the other end to trunk
Connects with SONET or SDH
10-15%

2. What is 802.1x force-unauthorized?
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server
Group (0-255) - priority (1-254 254 is highest - 100 default)
Port is forced to never authorize any connected client
It is enabled by default on all CEF capable switches

3. What is a topology change?
Trunk
When a port moves into forwarding or from fowarding or learning to blocking.
FE - GE - and aggregated FE/GE Etherchannels
Distribution

4. What is DSCP codepoint AF31(26)?
Flash (class 3)
When the AP uplinks to an Ethernet network.
Feature Manager - after the ACL is created - the FM compiles the ACEs into the table
MAC of the end device

5. What contains the next-hop entries?
FIB
224.0.0.2 (all routers)
802.11
The distribution layer should have only L3 links

6. How does IPT behave when the voice VLAN is in untagged mode?
Data and voice over native vlan - no QOS but still uses 802.1p trunk
Checks the sender's ip in all arp requests and checks the sender's IP against target IP in all replies
Checks the destination MAC in the header against the target MAC in the ARP reply
First configure a L3 interface in same VLAN as clients - then use the ip helper-address command to ID the DHCP server

7. What is the PVLAN host mode?
Each network device handles packets individually with no advance reservations
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
Some unused bits are used to allow a port to identify its role and state. Also the BDPUs state that they are V2 BDPUs
Only a single host connects . If one BDPU is received - it is no longer an edge port

8. RSTP learning state
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)
Turn on port security
If the switch or the powered device doesn't suport power class discovery
Incoming frames dropped - but MACs learned

9. What does the RP do?
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
An instance of RSTP running for each VLAN on the switch. Changing from PVST to RPVST+ is disruptive
Etherchannel ports have inconsistent config
Receives the first packet of a traffic flow and routes it

10. What is 802.1x force-authorized?
Embeds the tag within the frame
Connects to a router - firewall - or gateway. Can communicate with anything else connected to the primary or any secondary. Ignores pvlan config
1-client sends DHCP discover as broadcast - 2-DHCP server sends DHCP offer - client sends DHCP Request - DHCP server sends DHCP ack
The port is forced to always authorize any connected client with no authentication necessary (default)

11. How does every VRRP command begin?
Within a single MST region - an IST instances runs to work out a loop free topology between links where CST meets the region boundary and all switches in the region. It runs at the boundary.
Switch(config-if)# vrrp xx where xx= group number
Automatically by duplex mode in use. Full duplex are point ot point. Half duplex ports use traditional 802.1D convergence is used.
Global config (vlan - vtp mode - and vtp domain) and VLAN DB mode commands. Global config is preferred because VLAN DB mode commands are legacy

12. What address does HSRP send hello packets to?
All L2 connectivity should be contained within the access layer.
224.0.0.2 (all routers)
When a wireless station transmits a frame - the receiving one must send an ack
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged

13. RSTP discarding state
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
Can send and receive BDPUs
Incoming frames are dropped (combination of disabled - blocking - and listening)
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

14. What is an indirect topology change?
The link status stays up - but something between them has failed or is filtering traffic
1-lowest root bridge ID - 2-lowest root path cost - 3-lowest bridgeID - 4-lowest port ID
2-8 FE - GE - or 10GE are bundled.
3 seconds. Holdtime =3 hellos + 1

15. What does UDLD do?
Port is forced to never authorize any connected client
Root - designated - alternate - and backup
LACP port priority
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)

16. What is the cost of a 10Gbps link?
By using a trunk link
2
Used when ACLs specify port ranges...used by TCAM
No

17. How does uplinkfast handle changes in topology?
Notifies upstream neighbors by sending multicasts on behalf of hosts at the interval of the max update rate parameter.
Packets are discarded due to an ACL or policy action
Effectively stops STP on filtered ports
SC fiber or RJ-45

18. What is the GLBP redirect timer?
Determines when the AVG will stop using the old VMAC in ARP replies
Lowest cumulative cost to root
Dynamic arp inspection
0000.0c07.acxx where xx is the group number as a 2-digit hex value

19. What are the RSTP port states?
Discarding - learning - forwarding
Variation in delay
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
On the left as you face the connector

20. How does IPT behave when the voice VLAN is in vlan-id mode?
Source IP and MAC must match those addresses learned by DHCP snooping or a static entry
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root
Port with redundant - but less deisrable connection to a segment. Possibly root candidate
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p

21. What are the VRRP group and priority numbers?
Group (0-255) - priority (1-254 254 is highest - 100 default)
1500B
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover
By creating a static IP binding

22. How does the CEF L3 engine operate?

23. How is a WLC handoff handled when the WLCs are in different subnets?
By using an Ether-IP tunnel
Source IP - dest IP - combination of source and dest IP - source and dest MAC - or TCP/UDP port numbers
802.11
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

24. If a port is configured for errdisable auto recovery - how long does it stay down?
The wireless clients communicate directly with no other means of connectivity such as a WAP
Nonstop forwarding is an interactive method focusing on rebuilding the RIB after SUP switchover
300 sec by default
The distribution layer should have only L3 links

25. What are the 3 RSTP port types?
Tracks of BDPUs on nondesignated ports. When those BDPUs stop coming - the port is put into loop-inconsistent state and blocks
Edge - root - and point to point
No
Trunk

26. What does port-security protect do?
Access
If any BDUP is received on a port - it puts the port into the errdisable state
Port stays up - packets from violating MACs dropped - no logging
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

27. What is the size of a TCAM value?
134 bits - consisting of source and destination addresses and protocol information from the packet or frame
Determines when the AVG will stop using the old VMAC in ARP replies
Trunk
The standby becomes active and stays active by default. Preemption can be configured

28. What cabling do GBICs use?
Port
SC fiber or RJ-45
Used to switch packets that can't be forwarded normallly due to an encapsulation failure - unresolved address - unsupported protocol - etc.
Globally

29. What is best effort delivery QOS?
Controls where candidate root bridges can be connected and found on a network
Switches make an effort to move packets as quickly as possible
Etherchannel ports have inconsistent config
Root - designated - blocking - alternate - forwarding (host)

30. Define HSRP
Host Standby Router protocol. Cisco proprietary. Switch is either active - standby - or listen
Data goes over native vlan - voice goes over VLAN0 - voice QOS is 802.1p
Each frame transmits its expected duration time
Within a single MST region - an IST instances runs to work out a loop free topology between links where CST meets the region boundary and all switches in the region. It runs at the boundary.

31. What is step 1 of enabling IP source guard?
The number of times the entry has been updated since the table was generated
After forwarding delay - port can learn new MAC addresses
Cisco proprietary. 1 instance of STP/VLAN. Requires ISL instead of dot1q
Configure and enable DHCP snooping

32. RSTP backup port
RADIUS
Port with redundant - but less deisrable connection to a segment. Possibly root candidate
The ASIC
1-65535 (def 32768) lower priority - higher probability

33. How can you load-balance with HSRP?
Used when ACLs specify port ranges...used by TCAM
Data goes over native vlan - voice goes over specified VLAN - voice QOS is 802.1p
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
On ports where you never expect to find a root bridge for a VLAN

34. At what layer should the WLC be connected?
On the left as you face the connector
The time that a port spends in both listening and learning states . Default 15 seconds
Distribution
Determines when the AVG will stop using the old VMAC in ARP replies

35. What are the 5 STP states?
Access
Disabled - blocking - listening - learning - forwarding
Connects with SONET or SDH
Access or trunk

36. What is the default FE duplex?
Allows devices to interoperate with PVST and CST. Can use both dot1q and ISL
Differentiated services
The point at which a switch decides to trust incoming Qos. Usually at boundary with ISP
Full duplex

37. How do you configure IP source guard for hosts that don't use DHCP?
The priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)
By creating a static IP binding
Cisco ILP and 802.3af
If three are missed in a row - the neighbor is considered down and the data for that neighbor is aged

38. Where are security and QoS ACLs stored?
To a VLAN and not to a VLAN interface (SVI)
TCAM
Routers are assigned to common GLBP group. All routers can be active and can load balance
Manually

39. What is errdisable dtp-flap?
Change in trunk encap
Critical...used most often for IPT
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
1500B

40. What happens when switches receive a configuration BDPU?
Interim solution - uses same hardware as WEP - but uses TKIP encryption
A private VLAN can be logically associated with a special secondary vlan
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
2 strand MMF with MT-RJ or SC connectors

41. What is an IBSS?
900 MHz - 2.4Ghz - and 5-6GHz
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
All ports where root isn't expected
The wireless clients communicate directly with no other means of connectivity such as a WAP

42. How does every GLBP command begin
Root - designated - blocking - alternate - forwarding (host)
Almost eliminates listening and learning states for single hosts on an access link
Switch(config-if)# glbp xx where xx = group number
By brining up a tunnel between them to carry 802.11 related messages and client data.

43. static vlans offer ____ based membership
Two distribution switches that aggregate one or more access switches
Connects to a host on an isolated or community vlan. Communicates only with promiscuous port or ports on same community vlan
300 sec
Port

44. What is the 80/20 rule?
The frame tag includes a 3 bit COS value from 0 (low) to 7 (high). Native vlans are untagged so no COS
The active router. All other routers are in backup state
80% of the user traffic should stay in the VLAN
Yes to both

45. Does GLBP allow preemption?
Yes
Using digital certificates
Using a single WAP to centralize access and control over a group of wireless devices.
Sets the switchport mode to access - enables portfast - and turns off channel grouping for the port

46. RSTP alternate port
BGP - EIGRP - OSPF - and IS-IS.
Half because transmitting and receiving stations use the same frequency
Receives the first packet of a traffic flow and routes it
Port with alternative path to root less desirable than root

47. What is an end to end vlan?
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
A VLAN that spans the entire fabric
1-65535 (def 32768) lower priority - higher probability
Yes

48. What is the STP learning state?
Determines when the AVG will stop using the old VMAC in ARP replies
Limits the number if dhcp requests on a port
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
After forwarding delay - port can learn new MAC addresses

49. When looking at the sh spanning tree output - What does P2P peer(STP) denote?
A point to point port type but the neighboring device runs traditional 802.1D STP
1-name the chain - 2-establish a key number - 3-create the key string - 4-apply the chain to the string
Checks the source MAC in the header against the sender MAC in the ARP reply
Based on priority (0-255). Default is 100. Highest IP is tie breaker

50. What is a proxy arp?