Networking Terminologies Quiz

Study Notes

LAN: Local Area Network, a network covering a small geographic area.
VLAN: Virtual Local Area Network, a logical subgroup within a LAN for network segmentation.
SFD: Start Frame Delimiter, a 1-byte sequence (10101011) used to signal the start of an Ethernet frame.
FCS: Frame Check Sequence, error-checking mechanism in Ethernet frames.
MAC: Media Access Control, a 6-byte (48-bit) physical address unique to network devices.
BIA: Burned-In Address, the MAC address permanently programmed into a device.
OUI: Organizationally Unique Identifier, identifies manufacturer of the device's MAC address.
CRC: Cyclic Redundancy Check, used for error-checking data integrity.
ARP: Address Resolution Protocol, used to map IP addresses to MAC addresses.
CSMA/CD: Carrier Sense Multiple Access with Collision Detection, protocol for network access.
DSCP: Differentiated Services Code Point, used for QoS prioritization.
QoS: Quality of Service, improves performance of specific applications on the network.
ECN: Explicit Congestion Notification, indicates network congestion without dropping packets.
TTL: Time to Live, limits the lifespan of data in a network.
IHL: Internet Header Length, specifies the length of the IPv4 header.
TCP/UDP: Transmission Control Protocol / User Datagram Protocol, protocols for data transmission.
ISL: Inter-Switch Link, a Cisco proprietary protocol for VLAN tagging.

Connection Types:
- Straight Through: Connects switch to router, PC, or server.
- Crossover: Connects switch to switch, hub to hub, or PC to PC.
Ethernet Frame Structure:
- Preamble: 7-byte pattern for synchronization.
- SFD: Marks the end of the preamble.
- Destination & Source Address: Contains MAC addresses of sending and receiving devices.
- Type or Length: Indicates the type of encapsulated packet or its length.
Frame Issues:
- Runts: Frames smaller than 64 bytes.
- Giants: Frames larger than 1518 bytes.
- CRC Error: Frames that fail FCS error check.

Network Layer Functions: Connectivity, logical addressing (IP), and path selection via routers.
Routing Types:
- Dynamic Routing: Automatically shares routing info using protocols (e.g., OSPF).
- Static Routing: Manually configured routes by an administrator.
Address Types:
- Network Address: All 0s in host portion, cannot be assigned.
- Broadcast Address: All 1s in host portion, cannot be assigned.
- Loopback Address: 127.0.0.0 to 127.255.255.255 used for testing.
IPv4 Header Specifications:
- IHL: Ranges from 20 to 60 bytes; minimum value is 5.
- DSCP & ECN fields: For QoS and congestion notification.
- Total Length: Indicates packet size ranging from 20 to 65,535 bytes.
- Identification Field: Used for fragment identification.
- Flag Field: Controls fragmentation behavior.
- TTL Field: Prevents infinite loops; default is typically 64.
- Protocol Field: Defines encapsulated protocol (TCP #6, UDP #17).
- Checksum Field: Verifies header integrity.
- Source & Destination Addresses: Indicate packet sender and intended recipient.

Definition of Routing: The process for determining the best path for IP packets to reach their destination.
Routing Table: Contains routes to known destinations.
Next Hop: The next router along the path to the destination.
Routing Codes:
- L: Local route (the router’s own address).
- C: Connected route (network interface connection).
Default Gateway: Configured as 0.0.0.0/0, used when no specific routes exist.

Definition of VLAN: A logical grouping of devices within a broadcast domain for segmentation.
Broadcast Domain: Group of devices receiving broadcast frames; excessive broadcasts can impair performance.
Port Types:
- Access Port: Connects to a single VLAN and end devices.
- Trunk Port: Carries multiple VLANs between switches, tagged for identification.
VLAN Tagging: Allows switches to manage traffic for different VLANs on a single link.
Trunking Protocols:
- ISL: Older Cisco proprietary protocol for inter-switch VLAN communication.