Exam Revision Flashcards
What is the purpose of configuring an SVI interface on a switch?
A Switched Virtual Interface (SVI) is routed interface in IOS representing the IP addressing space for particular VLAN connected to this interface. There is no physical interface for the VLAN and the SVI provides the Layer 3 processing for packets from all switch ports associated with the VLAN.
What is the difference between half duplex and full duplex communication?
Full-duplex communication increases bandwidth efficiency by allowing both ends of a connection to transmit and receive data simultaneously.
Half-duplex communication unidirectional. Half-duplex communication creates performance issues because data can flow in only one direction at a time.
What is the major difference between the Telnet and SSH protocols?
Telnet (using TCP port 23) is an older protocol that uses unsecure plaintext transmission of both the login authentication (username and password) and the data transmitted between the communicating devices.
SSH (using TCP port 22) provides security for remote connections by providing strong encryption when a device is authenticated (username and password) and also for the transmitted data between the communicating devices.
When are directly connected routes added into the routing table?
Routers add a directly connected route when an interface is configured with an IP address and is activated.
How does a switch learn what entries to place in its addressing table?
A switch builds a MAC address table by reading the source MAC address into the table along with the port it was received.
Examines Source Address
If not in table, adds the source MAC (along with the port it was received)
If source MAC is already in the table, resets the time-out setting back to 5 minutes.
What is Store-and-forward switching?
Store-and-forward switching receives the entire frame and ensures the frame is valid. Store-and-forward switching is Cisco’s preferred switching method.
What is Cut-through switching?
Cut-through switching forwards the frame immediately after determining the destination MAC address of an incoming frame and the egress port.
Advantages and disadvantages of store-and-forward switching?
Advantage is that there is a high level of error-free data transmission as error checking is supported, as is automatic buffering so the entire frame will be stored.
Disadvantage is that the switch latency (waiting time) is a little longer as it takes times to store the entire frame in the switch.
Advantages and disadvantages of cut-through switching?
Advantage is that the switch latency is very low because the switch will not store the entire frames or packets.
Disadvantage is invalid frames exist. Ethernet frames with or without errors will be forwarded to the destination port if its first 6 bytes are recognised. Bad frames will be forwarded too, which will cause error frames.
What is the boundary of a broadcast domain?
A broadcast domain extends across all Layer 1 or Layer 2 devices on a LAN.
Only a Layer 3 device (router) will break the broadcast domain, also called a MAC broadcast domain.
What is an access port? When is it typically used?
An access port can belong to one data VLAN at a time. It can carry traffic from only one VLAN. It is typically connected to an end-device.
What is an trunk port? When is it typically used?
A trunk port is in permanent trunking mode. It is a Layer 2 link between two switches that carries traffic for all VLANs.
A trunk is a point-to-point between two network devices. They extend the VLAN across the entire network.
Trunk ports are the links between switches that support the transmission of traffic associated with more than one VLAN.
What is the effect on the size of broadcast domains when the ports of a switch are subdivided into a number of VLANs?
It creates smaller broadcast domains. If a device in one VLAN sends a broadcast Ethernet frame, all devices in the VLAN receive the frame, but devices in other VLANs do not.
With IEEE 802.1Q, how is traffic for the native VLAN distinguished from traffic for other VLANs?
All frames are tagged on an 802.1Q trunk link except for those on the native VLAN.
The switch assigns any untagged frame that arrives on a tagged port to the native VLAN. If a frame on the native VLAN leaves a trunk (tagged) port, the switch strips the VLAN tag out.
What is the difference between a management VLAN and a native VLAN? When is each used?
The Management VLAN is used for SSH/Telnet VTY traffic and should not be carried with end user traffic. It is the VLAN that is the SVI for the Layer 2 switch.
The Native VLAN is used for trunk links only. All frames are tagged on an 802.1Q trunk except for those on the native VLAN.
