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What pins do Switch receivers use?
The pair connected to pins 1 and 2
How many bytes are the Ethernet header and trailer?
Header = 22 + Trailer = 4 == 26 bytes
What is the PoP?
Point of Presence: Nearby SP location that connects to the customer building
What is the primary purpose of a VLAN?
To create a broadcast domain; enable segmentation or isolation of broadcast traffic
Unassigned Cisco switch ports remain in which VLAN?
VLAN 1
Do VLANs prevent broadcast storms?
No, they minimize the size and effect of the broadcast storm on neighbor switches and hosts
What are four advantages to using VLANs?
1. Enable access to network services based on logical requirements
2. Network security is optimized with VLANs that enable managing and filtering sensitive traffic from other network traffic
3. Bandwidth efficiency is accomplished through segmenting traffic into smaller broadcast domains
4. Easier add/move/delete administration of endpoints on a network and scalability for larger enterprise deployments
What is the Layer 2 Broadcast Destination Address?
FFFF.FFFF.FFFF
What is the Layer 3 Broadcast Destination Address?
255.255.255.255
What is VLAN 1 used for and can it be deleted?
Management Traffic; it cannot be deleted
What is the normal VLAN range?
VLAN 2 - 1001
What is the extended VLAN range?
VLAN 1006 - 4094
What VLANs are auto-created and cannot be deleted?
VLAN 1, 1002 - 1005
What VLANs cannot be pruned from a trunk?
VLAN 1006 - 4094
How many VLANs can be assigned to a switch access port?
Only one VLAN unless you are connecting an IP phone
What commands would you use to setup a switch access port with an IP phone?
interface <interface#/#>
switchport mode access
switchport access vlan #
switchport voice vlan #
Where is the switch VLAN configuration stored?
vlan.dat file
What commands would you use to globally create and name a VLAN?
vlan #
name <name_of_vlan>
What is the default switch port mode?
Access port
What will switch access ports do with am Ethernet frame it receives with an 802.1q tag?
It will discard the packet without learning the source MAC address
What command would you use to configure a range of switch ports?
interface range gigabitethernet#/# - #
What command lists all VLANs configured on a switch?
show vlan or show vlan brief
What command is used to display the switch ports assigned to a single VLAN?
show vlan id <vlan>
When are data messages forwarded to the default gateway?
When the destination subnet is on a different subnet than the endpoint
Does the Cisco default switch configuration have an IP default gateway?
No
What command is used to create an IP default gateway?
ip default-gateway <ip_address>
What is the primary purpose of a switch?
To make forwarding decisions based on destination MAC address
List the network services provided by switches
- Only read Ethernet frame headers and forward traffic
- Create and maintain the MAC address table
- Create separate collision domains per switch port
- Create separate broadcast domains per VLAN
What method was used for detecting Ethernet collisions on older hubs and bridges?
Carrier Sense Multiple Access Collision Detection (CSMA/CD)
How many separate MAC address table does a switch create?
A switch creates a separate MAC address table for each configured VLAN
What command lists the contents of the MAC address table for a switch?
show mac address-table
When does a switch begin MAC address learning?
When a switch is first started and connected hosts start sending frames? Also triggered when the aging time expires for an address
What is the default time that a switch removes MAC address table entries?
300 seconds
How do you disable MAC address table aging?
Configure the MAC aging timer to zero
What are the steps when a host sends data to a server on the same VLAN for the first time?
1. Switch adds the source MAC address of incoming frame if it is not listed in the MAC address table
2. Switch does a MAC address table lookup for the destination MAC address
3. Switch floods a frame using FFFF.FFFF.FFFF as destination MAC address out all switch ports except the port where the source MAC address was learned
4. Server wit the assigned MAC address responds with a frame that lists the MAC address
5. Switch updates the MAC address table with the MAC address of the server; That is the destination MAC address for frames sent from the host
6. Switch forwards the frames from the host to the server based on the switch port assigned to the server
What is Cut-Through Switching?
It is a technique that optimizes performance by examing only the first 6 bytes (destination MAC address) of an Ethernet frame before making a forwarding decision. The switch does a MAC address table lookup for the destination MAC address and forwards the frame.
What is the advantage of Cut-Through Switching?
The forwarding decision is made before all of the frame arrives and thereby minimizes latency
What is Store-and-Forward Switching?
Traditional switching where the frame is not forwarded until all of the frame has arrived. The switch copies the frame to memory before examining the destination MAC address and forwarding the frame.
What is CEF?
Cisco Express Forwarding: Layer 3 switching technique that creates FIB and adjacency tables for optimized forwarding. It is only available on routers and switch platforms with routing enabled and the required hardware
What is an FIB?
Forwarding Information Base: Used by CEF to mae IP destination prefix-based switching decisions. Conceptually similar to a routing table or information base. It maintains a mirror image of the forwarding information contained in the IP routing table.
Which devices can perform frame rewrite?
Layer 3 switches and Wireless LAN Controllers
Which devices perform frame switching?
Layer 2 switches and Access Points
What are the duplex and speed default settings on a switch port?
auto-negotiation
What is the purpose of a switch trunk?
To forward multiple VLANs between switches
What command enables trunking on an interface?
switchport mode trunk
encapsulation dot1q
What does the native VLAN forward?
Control traffic across switch trunks
Why is it recommended to change the native VLAN?
This is a Cisco security best practice as there are security vulnerabilities associated with default VLAN 1; STP issues are minimized as well by selecting a nondefault VLAN instead of VLAN 1
What command changes the native VLAN?
switchport trunk native vlan <vlan_id>
What is the purpose of VLAN pruning?
To permit or deny VLANs across a switch trunk
What is the Cisco default for VLAN pruning
To allow all VLANs across the trunk
What command sets a range of VLANs to an interface?
switchport trunk allowed vlan <#>-<#>
What are the three modes of DTP?
nonegotiate, desirable, auto
Is DTP enabled by default on switch ports?
Yes
What does a switch port configured with desirable mode do?
Actively sends DTP frames to negotiate trunk with neighbor switch
What is the operation of switchport mode access?
Access port only (no trunk) - only one VLAN, two if you include a Voice VLAN
What is the operation of switchport mode trunk?
Trunk statically formed and no DTP frames sent
What is the operation of switchport mode dynamic auto?
Listens for DTP requests
What is the operation of switchport mode dynamic desirable?
Listens and sends DTP requests
What is the operation of switchport nonegotiate?
Disables DTP
What intervals are DTP frames sent?
One second intervals during negotiation and every 30 seconds after that
DTP auto mode - auto mode
Default, results in no trunk
DTP auto mode - desirable mode
Trunk negotiated
DTP desirable mode - desirable mode
Trunk negotiated
What does EtherChannel do?
Bundles multiple physical switch links between switches into a single logical link.
What is EtherChannel also referred as?
Switch Port Aggregation
What are the advantages of EtherChannels?
Fault tolerance (redundancy) and high speed connectivity between switches
What is the maximum number of ports Cisco switches support to a single EtherChannel bundle?
8 ports
What is the maximum number of ports LACP supports to a single EtherChannel bundle?
16 ports, however only 8 ports can be active simultaneously
What is LACP?
Link Aggregation Control Protocol, within the IEEE specification, provides a method of control the bundling of several physical ports together to form a single logical channel. It allows a network device to negotiate an automatic bundling of links by sending LACP packets to the peer
What are the options for configuring an EtherChannel?
Static or Dynamic Protocols
What are the layers of a fiber cable inside going outward?
Core, Cladding, Buffer, Strengthener, Outer Jacket
How many bytes and purpose of the Type in an Ethernet header?
2 bytes - defines the type of protocol listed inside the frame; today, most likely identifies IPv4 or IPv6
What field(s) are in the HDLC trailer?
Frame Check Sequence (FCS)
How many commands are stored in the history buffer by default?
10 commands
How do you create local users & associated them to lines?
'username <name> password <pass>'
'line <line> #'
'login local'
How do you give an SVI DHCP?
'int vlan 1'
'ip address dhcp'
What is the difference between static and dynamic EtherChannel configurations?
Static does not provide any dynamic trunk negotiation
What are the four supported modes of LACP?
On, off, active, and passive
What does the channel-group bind?
The port channel interface to an EtherChannel
What is a Layer 2 port channel?
Logical interface comprised of EtherChannel access ports or trunk ports
How is the Layer 2 port channel created?
It is created automatically based on the channel-group number
What are the supported channel-group numbers?
1 - 4096
What is a Layer 3 port channel?
Routed logical interface comprised of EtherChannel access ports or trunk ports
What is Active mode in LACP?
The active end of the group sends out a LACP frame and initiates the negotiation to form the EtherChannel. Both ends could be active and the result will be the same
What is Passive mode in LACP?
Does not initiate the negotiation, it just responds to LACP packets initiated by the other end. If both ends are passive, the EtherChannel would bot be formed
What is PAgP?
Port Aggregation Protocol: Cisco proprietary networking protocol, which is used for the automated, logical aggregation of Ethernet switch ports
What is the default mode for LACP?
Passive Mode
What is the default mode for PAgP?
Auto Mode
What layer of the TCP/IP model does HTTP belong?
Application Layer
What layer of the TCP/IP model does POP3 belong?
Application Layer
What layer of the TCP/IP model does SMTP belong?
Application Layer
What layer of the TCP/IP model does TCP and UDP belong?
Transport Layer
What layer of the TCP/IP model does ICMP belong?
Internet Layer
What does the Application Layer define?
Does not define the applications itself, but it defines services that applications need. The Application Layer provides an interface between software running on a computer and the network itself.
What does the return code 200 mean in an HTTP header?
OK
What does the return code 404 mean in an HTTP header?
Not found
What layers of the OSI model do not exist in the current TCP/IP model?
Session and Presentation Layers (5 and 6)
What standard is 802.3?
Ethernet
In an Informal IEEE Standard Name, what does the T stand for (example: 1000BASE-T)?
Unshielded Twisted Pair (UTP)
In an informal IEEE Standard Name, what does the X stand for (example: 1000BASE-LX)?
Fiber
