Networking Flashcards
(38 cards)
What are the IPv4 address classes and their key characteristics?
IPv4 addresses are divided into classes based on the range of the first octet.
- Class A: First octet 0–127, binary starts with 0, default subnet mask 255.0.0.0, CIDR /8.
- Class B: First octet 128–191, binary begins with 10, default mask 255.255.0.0, CIDR /16.
- Class C: First octet 192–223, binary begins with 110, default mask 255.255.255.0, CIDR /24.
- Class D: First octet 224–239, binary begins with 1110, used for Multicast Addressing.
- Class E: First octet 240–255, binary begins with 1111, designated as Experimental.
What is the significance of IPv4 addresses being 32 bits long?
IPv4 addresses have 32 bits divided into four octets. This allows for approximately 4.3 billion unique addresses. The 32‐bit structure is represented in dotted-decimal notation, and it delineates network and host portions according to classful or CIDR-based subnet masks.
What are the private IP ranges in IPv4 and why are they important?
Private IP ranges are reserved for internal networks and are not routable on the public Internet. They include 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. Using these ranges helps conserve public IP addresses and enhances network security by isolating internal traffic from the public realm.
What is APIPA and why is it useful?
APIPA stands for Automatic Private IP Addressing. It allows a Windows machine to assign itself an IP address from the 169.254.0.0/16 range when no DHCP server is available. This DHCP fail-safe mechanism enables devices on a LAN to communicate locally even when external configuration services are down.
What is the loopback address in IPv4 and what is its purpose?
The loopback address is defined within the 127.0.0.0/8 range, with 127.0.0.1 being the most commonly used address. It is used to test network software without sending packets over a physical network, essentially allowing a device to communicate with itself.
How are IPv6 addresses structured and what advantages do they offer?
IPv6 addresses are 128 bits long and are written as eight groups of four hexadecimal digits separated by colons. The extended address space allows for a virtually unlimited number of unique addresses. Additionally, shorthand notation using a double colon (::) can compress contiguous sections of zeros, making addresses shorter and easier to read.
List the different types of IPv6 addresses and their purposes.
IPv6 address types include: • Unspecified (::/128) for representing an absence of an address; • Loopback (::1/128) for local testing; • Unique Local Addresses (FC00::/7) for private networks; • Link-local addresses (FE80::/10) for communication on a single network segment; • Global unicast addresses (2000::/3) for routable addresses on the Internet; • Multicast addresses (FF00::/8) to send data to multiple recipients simultaneously.
What mechanisms allow IPv4 and IPv6 to coexist on the same networks?
Dual Stacking allows devices to run both IPv4 and IPv6 concurrently. Tunneling encapsulates IPv6 packets within IPv4 packets (methods include 6to4, 6in4, Teredo, and ISATAP), while translation through routers converts header information between the protocols to enable communication.
Why is subnetting critical in network design?
Subnetting breaks a larger network into smaller subnets, which optimizes network performance by reducing broadcast domains, improving security, and facilitating efficient IP address allocation. It requires careful calculation of the first, last, network, and broadcast addresses for each subnet.
What is the OSI Model and why is it crucial in understanding network communication?
The OSI (Open Systems Interconnection) Model is a conceptual framework that divides network communication into seven layers. Each layer has a specific function and standardized protocols, allowing interoperability, simplified troubleshooting, and modular network design across different vendors and technologies.
What is the role of the Application Layer (Layer 7) in the OSI Model?
Layer 7, the Application Layer, provides services directly to end-user applications. It acts as the interface between software applications and the underlying network, supporting protocols such as DNS, HTTP, FTP, SMTP, POP3, SNMP, and Telnet to facilitate communication and data exchange.
Describe the functions of the Presentation Layer (Layer 6).
The Presentation Layer ensures that data is in a usable format and handles translation between different data formats. It is responsible for data compression, encryption, decryption, and character encoding conversion, ensuring that data sent by the Application Layer of one system can be properly interpreted by the Application Layer of another. Protocols like SSL/TLS operate here.
Explain the responsibilities of the Session Layer (Layer 5).
The Session Layer manages and controls the dialogue between two devices. It sets up, coordinates, and terminates connections (sessions) across the network while handling the exchange and synchronization of data. This layer uses protocols like NetBIOS, RPC, and PPTP to facilitate effective communication between applications.
What functions does the Transport Layer (Layer 4) perform?
The Transport Layer provides transparent transfer of data between end systems, ensuring complete data transfer with error detection, correction, and flow control. It segments data for transmission (TCP uses connection-oriented communication with features such as sequence numbers and acknowledgments, while UDP offers a faster, connectionless service for applications where speed is more critical than reliability).
How does the Network Layer (Layer 3) facilitate data routing?
The Network Layer is responsible for logical addressing (using IP addresses) and routing across multiple networks. It determines the best path for data packets to travel from the source to the destination and handles fragmentation and reassembly if packets are too large. Routers operate at this layer, and protocols such as IP, ARP, and ICMP are key components.
What roles do the Data Link (Layer 2) and Physical (Layer 1) layers serve in the OSI Model?
The Data Link Layer (Layer 2) is responsible for node-to-node data transfer, framing, error detection, and MAC addressing, while the Physical Layer (Layer 1) deals with the transmission of raw bits over physical media such as cables, fiber optics, or wireless channels. Together, they ensure that data is delivered accurately across the shared medium.
What functions do common network devices perform?
• A Network Adapter (NIC) enables a computer to connect to a network at the Data Link Layer. • Repeaters amplify signals to overcome attenuation at the Physical Layer. • Hubs act as multiport repeaters that broadcast signals to all connected devices. • Switches examine MAC addresses to forward data to the appropriate port (Layer 2). • Routers operate at the Network Layer to route traffic between disparate networks and manage data paths.
Compare the physical network topologies of bus, ring, star, and full mesh.
• In a Bus topology, all devices share a single communication line; if the main cable fails, the entire network collapses. • A Ring topology connects each device to two others in a closed loop; token-based transmission is used, but a single failure can disrupt the network. • A Star topology links all devices to a central hub; if a peripheral fails, the impact is isolated, though a central hub failure can bring down the network. • In a Full Mesh topology, every device is interconnected, providing high redundancy and fault tolerance at the expense of increased wiring and complexity.
What are the three ranges of port numbers and what is their significance?
Port numbers are divided into three ranges for standardization: • Well-Known Ports (0–1023): Used by core services and applications (e.g., HTTP, FTP). • Registered Ports (1024–49151): Assigned for user or application-specific services. • Private/Dynamic Ports (49152–65535): Utilized for temporary, short-lived connections and private communications.
What is ARP and how does it function in a network?
ARP (Address Resolution Protocol) is used to map an IP address to its corresponding physical (MAC) address on a local network. This mapping enables data packets to be correctly delivered within a network. Reverse ARP (RARP) performs the opposite function by finding the IP address corresponding to a given MAC address.
Summarize the key aspects of the FTP protocol.
FTP (File Transfer Protocol) is used to transfer files between a client and server. It operates using separate control (TCP port 21) and data (TCP port 20) connections. FTP supports authentication and specifies file transfer parameters using a standardized URL format (ftp://[user]:[password]@[host]:[port]).
What is SSH and why is it preferred over Telnet?
SSH (Secure Shell) is a protocol for secure remote login and data communication. It encrypts data to protect sensitive information and operates on TCP port 22. Unlike Telnet, which sends text in clear, SSH offers robust security by employing modern encryption methods and key exchange protocols.
What role does DNS play in networking and which ports does it use?
The Domain Name System (DNS) translates human-readable domain names into IP addresses that computers can use to communicate. It primarily uses UDP on port 53 for queries and TCP on port 53 for tasks such as zone transfers, ensuring that address resolution is efficient and scalable.
How does DHCP simplify network management?
DHCP (Dynamic Host Configuration Protocol) automates the assignment of IP addresses and other network configuration details (such as the default gateway and DNS servers) to devices on a network. It operates using UDP ports 67 (server) and 68 (client), reducing the need for manual configuration and ensuring consistent network settings.
