Cisco Certified Support Technician (CCST) Networking flashcards

A Cisco switch feature that allows a single access port to carry traffic for both an IP phone (in a dedicated voice VLAN with QoS) and a connected PC (in a data VLAN).

• Automatically configures QoS for voice traffic.
• Simplifies deployment of IP phones.
• Requires the IP phone to support discovery protocols like CDP or LLDP-MED.

Memory trick: Voice VLAN: one port, two hats for phone and PC.

An IEEE 802.11 amendment designed to speed up the handoff process between access points in a wireless network, enabling seamless roaming.

• Minimizes re-authentication time for clients.
• Crucial for voice-over-Wi-Fi (VoWiFi) and real-time applications.
• Implemented on both APs and client devices.

Memory trick: Roaming 'R'equires 'R'apid 'R'econnection.

A common Ethernet connectivity issue where one end of a link operates in full-duplex mode and the other operates in half-duplex mode.

• Results in late collisions, frame errors, and retransmissions.
• Causes severe network performance degradation.
• Often happens when auto-negotiation fails or is misconfigured.

Memory trick: Duplex mismatch: half-talk, full-listen, total confusion.

Voice VLANs are used to separate IP phone traffic from data traffic on the same switch port, ensuring QoS for voice and simplifying network management.

• IP phones typically have a built-in 3-port switch (one for switch, one for phone, one for PC).
• Uses 'switchport voice vlan [vlan-id]' command on Cisco switches.
• Phone learns voice VLAN ID via CDP or LLDP-MED.
• Ensures voice traffic is tagged with the correct VLAN ID.

Memory trick: Voice VLAN Missing, Phone's Not Listening

A high-performance, scalable WAN technology that speeds up network traffic flow by using labels to forward data packets, allowing for efficient routing, QoS, and VPN services over a service provider's network.

• Uses labels for efficient packet forwarding
• Supports QoS for different traffic types
• Scalable and flexible for various services (VPNs)
• Commonly offered by service providers

Memory trick: MPLS labels guide traffic with QoS.

An IEEE standard for Power over Ethernet that delivers up to 30 watts of power per port over standard Ethernet cables, supporting devices like IP phones, wireless access points, and PTZ cameras.

• Provides up to 30W per port
• Backward compatible with 802.3af (PoE)
• Commonly used for IP phones and WAPs
• Requires Cat5 or higher cabling

Memory trick: af=phone, at=AP, bt=big devices.

Two primary frequency bands used for Wi-Fi, each with distinct characteristics regarding speed, range, and interference.

• 2.4 GHz: longer range, better penetration, more interference, lower speed.
• 5 GHz: shorter range, worse penetration, less interference, higher speed.
• Higher frequencies mean shorter wavelengths, leading to more attenuation.

Memory trick: 5 GHz is fast but short-legged; 2.4 GHz is slow but a marathon runner.

A WAN technology that uses communication satellites to provide internet access, typically used in rural or remote areas.

• Offers wide geographic coverage.
• Typically has higher latency due to signal travel distance.
• Can be affected by weather conditions.
• Often a last-resort option where wired broadband is unavailable.

Memory trick: When roads end, look to the sky for internet.

The manner in which electromagnetic waves travel through a physical medium and interact with environmental factors such as obstacles, leading to effects like reflection, absorption, diffraction, and scattering.

• Affected by physical objects (walls, metal)
• Causes attenuation (signal loss)
• Leads to reflection, refraction, diffraction, scattering
• Directly impacts wireless coverage and signal strength

Memory trick: Propagation is the signal's journey through obstacles.

The IP address of the router interface on a local network segment that acts as a forwarding host to other network segments or the internet.

• Required for inter-VLAN/inter-subnet communication
• Must be on the same subnet as the host
• Traffic to non-local destinations is sent here

Memory trick: Gateway is the bridge to other VLANs.

Specific settings that must be identical across all physical interfaces intended to form a logical EtherChannel bundle.

• All interfaces must have the same speed and duplex.
• All interfaces must be in the same mode (access or trunk).
• If trunking, all interfaces must have the same native VLAN and allowed VLANs.
• Can bundle 2 to 8 active links.

Memory trick: All channels must match for a perfect bundle.

Actions a switch takes when an unauthorized device or too many MAC addresses are detected on a port configured with port security.

• Protect: drops unauthorized traffic.
• Restrict: drops unauthorized traffic, sends SNMP trap, increments counter.
• Shutdown: disables the port and puts it in err-disable state.

Memory trick: P-R-S: Protect, Restrict, Shutdown – each more severe.

The ability of newer Wi-Fi standards (e.g., 802.11ax) to connect and communicate with older Wi-Fi standards (e.g., 802.11n) at the capabilities and speeds of the older standard.

• Newer devices can connect to older APs
• Performance limited to the older standard's capabilities
• Advanced features of newer standard are not utilized
• Older APs may not efficiently handle newer client devices

Memory trick: New car, old road: it still drives, but no speed limit breaking.

The 2.4 GHz Wi-Fi band has limited non-overlapping channels, making careful channel selection crucial for avoiding interference in multi-AP deployments.

• In North America, channels 1, 6, and 11 are the standard non-overlapping 2.4 GHz channels.
• Each channel occupies 22 MHz, and they are spaced 5 MHz apart.
• Overlapping channels cause co-channel interference, reducing performance.

Memory trick: One-Six-Eleven: Keep Wireless Heaven!

A type of interference in wireless networks where multiple access points or devices operate on the same frequency channel within the same geographic area, leading to signal collision, reduced throughput, and increased retransmissions.

• Occurs when APs share the same channel
• Common in dense 2.4 GHz environments
• Causes reduced throughput and increased latency
• Mitigated by proper channel planning (non-overlapping channels)

Memory trick: Co-channel collision, Adjacent channel overlap.

The Physical Layer (Layer 1) deals with the physical connection between devices. Basic checks include cable integrity, port status, and power.

• Link lights indicate physical connection status.
• No link light usually points to a cable or port issue.
• Always start troubleshooting with the lowest layer of the OSI model.

Memory trick: Cable's Dead, Link's Gone, Check the Port, Get it On!

A leased line is a dedicated, private, point-to-point connection provided by an ISP, offering guaranteed bandwidth and service levels for WAN connectivity.

• Dedicated circuit, not shared.
• Symmetric bandwidth (upload = download).
• Guaranteed bandwidth and Service Level Agreements (SLAs).
• Higher cost compared to shared services.

Memory trick: Dedicated, Symmetric, Guaranteed: Business WAN's Best Friend

Cisco switches use different port modes (access, trunk, dynamic) to manage how VLAN traffic is handled on a port.

• Access port: Carries traffic for only one VLAN, typically for end devices.
• Trunk port: Carries traffic for multiple VLANs, typically for switch-to-switch or switch-to-router connections.
• VLANs provide logical segmentation of networks.

Memory trick: Access for Users, Trunk for Switches

A wireless network configuration where multiple Service Set Identifiers (SSIDs) are broadcast from a single Access Point, with each SSID being associated with a distinct VLAN for traffic segmentation.

• Allows multiple virtual wireless networks
• Each SSID maps to a unique VLAN
• Provides traffic segmentation and isolation
• Requires the AP to be connected to a trunk port on the switch

Memory trick: Each SSID gets its own VLAN house.

Wi-Fi signal propagation characteristics, including range and penetration, vary significantly between 2.4 GHz and 5 GHz bands, impacting network design in different environments.

• Lower frequencies (2.4 GHz) have longer wavelengths, better obstacle penetration, and longer range.
• Higher frequencies (5 GHz) have shorter wavelengths, worse obstacle penetration, and shorter range.
• Metal objects are particularly effective at blocking or reflecting Wi-Fi signals.

Memory trick: Lower Frequencies Punch Through, Higher Frequencies Get Stuck

Port Security is a Layer 2 security feature on switches that restricts input to an interface by limiting and identifying the MAC addresses of devices allowed to connect.

• Restricts access based on MAC addresses.
• Can be configured to learn MACs dynamically, statically, or sticky.
• Violation modes: shutdown, restrict, protect.
• Helps prevent MAC address spoofing and unauthorized access.

Memory trick: MAC Address Lock, No Rogue Devices Talk

VLANs logically segment a single physical LAN into multiple broadcast domains. This allows devices on different VLANs to communicate only through a router, even if they are on the same switch.

• Provide logical segmentation of a network.
• Improve security and performance by reducing broadcast traffic.
• Allow for flexible network design without physical relocation of devices.

Memory trick: Virtual Lanes Isolate Network

An enhanced twisted pair cable standard designed to support 10 Gigabit Ethernet (10GbE) over distances up to 100 meters, with improved performance against alien crosstalk and EMI.

• Supports 10 Gigabit Ethernet (10GbE)
• Maximum distance of 100 meters for 10GbE
• Operates at up to 500 MHz
• Enhanced resistance to alien crosstalk/EMI

Memory trick: Each Cat upgrades speed and distance.

A wireless frequency band that offers higher data rates, more available channels, and less interference compared to the 2.4 GHz band, but typically has a shorter range and poorer penetration.

• Higher bandwidth and data rates
• More non-overlapping channels
• Less interference from other devices
• Shorter range and poorer wall penetration

Memory trick: Fast 5 is short, Slow 2 is long.

A switch port configured to carry traffic for multiple VLANs over a single physical link, typically using 802.1Q tagging.

• Connects switches to other switches or routers.
• Allows VLANs to extend across multiple network devices.
• Uses encapsulation (e.g., 802.1Q) to identify VLANs.

Memory trick: Trunk: The multi-lane bridge for VLANs.

Occurs when multiple wireless devices or access points operate on the same frequency channel in overlapping areas, leading to performance degradation.

• Reduces effective throughput and increases latency.
• Especially problematic in the crowded 2.4 GHz band.
• Can be mitigated by using non-overlapping channels (1, 6, 11 in 2.4 GHz).

Memory trick: Too many voices on one channel leads to chaos.

EIGRP calculates a composite metric for path selection using several components, with Bandwidth and Delay being the default factors.

• Default components: Bandwidth and Delay.
• Optional components: Reliability and Load.
• Uses K-values (K1-K5) to weight these components.
• Lower metric values indicate a better path.

Memory trick: EIGRP's path choice depends on how fast and how long.

A passive interface in EIGRP prevents routing updates from being sent out or received on that specific interface while still allowing the network connected to it to be advertised by EIGRP.

• Prevents unnecessary routing updates on LAN segments.
• Enhances security by not sending updates to untrusted networks.
• Configured using the 'passive-interface <interface-type/number>' command under the EIGRP router configuration.

Memory trick: EIGRP interfaces can be chatty or quiet, choose wisely for security.

Static NAT creates a permanent one-to-one mapping between a private IP address and a public IP address, allowing external devices to initiate connections to an internal host.

• Uses 'ip nat inside source static <local-ip> <global-ip>'.
• Requires one public IP address per internal host.
• Commonly used for servers accessible from the internet.

Memory trick: NAT is like a translator, static is a fixed dictionary entry.

EMI is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. It can degrade network performance or even prevent a circuit from functioning.

• Caused by sources like power cables, fluorescent lights, and motors.
• Can lead to data corruption, intermittent connectivity, and reduced network speed.
• Shielded cables (STP) are more resistant to EMI than unshielded cables (UTP).
• Proper cable management and grounding help mitigate EMI.

Memory trick: Don't let electricity zap your network's flow!