1.4 Subnet & IP's Flashcards
RFC1918
RFC1918 defines private IP address ranges that are reserved for use within internal networks and are not routable on the public internet. These address ranges are used in home, business, and enterprise networks, allowing devices to communicate without requiring globally unique IP addresses. The three address ranges defined by RFC1918 are:
- 10.0.0.0 to 10.255.255.255 (Class A)
- 172.16.0.0 to 172.31.255.255 (Class B)
- 192.168.0.0 to 192.168.255.255 (Class C)
For the exam, you should know that RFC1918 addresses are commonly used with Network Address Translation (NAT) to allow private networks to communicate with public networks. Understanding these address ranges and their role in private network configurations is important for network design, troubleshooting, and managing IP address allocation.
- Network address translation (NAT)
Network Address Translation (NAT) is a process used in networking to modify IP address information in packet headers as they pass through a router or firewall. NAT allows multiple devices on a private network to share a single public IP address when accessing the internet. It translates private IP addresses (like those defined by RFC1918) to a public IP, enabling communication between internal devices and external networks.
For the exam, you should understand that NAT is essential for conserving public IP addresses and enhancing network security by masking internal IP addresses. You may also encounter terms like Static NAT (one-to-one mapping) and Dynamic NAT (many-to-one mapping), as well as Port Address Translation (PAT), which maps multiple private IP addresses to a single public IP using different ports. Knowing how NAT works, its types, and its role in network security and IP conservation is critical for network management and troubleshooting.
- Port address translation (PAT)
Port Address Translation (PAT) is a type of Network Address Translation (NAT) that allows multiple devices on a local network to share a single public IP address while using different port numbers to distinguish between connections. PAT works by modifying the source IP address and port number of outbound packets, enabling the router to track active connections from various internal devices.
For the exam, you should know that PAT is often referred to as “NAT overload” because it overloads a single public IP address with multiple internal IP addresses. This method is widely used in home and enterprise networks to conserve public IP addresses while allowing multiple devices to access the internet simultaneously. Understanding how PAT operates, its benefits in managing network traffic, and its role in enhancing security by obscuring internal IP addresses is important for effective network design and troubleshooting.
Automatic Private IP Addressing (APIPA)
Automatic Private IP Addressing (APIPA) is a feature in Windows operating systems that automatically assigns a private IP address to a device when it fails to obtain an IP address from a DHCP server. APIPA uses the address range of 169.254.0.1 to 169.254.255.254, allowing devices on the same local network to communicate without requiring manual configuration.
For the exam, you should know that APIPA is beneficial in small networks where a DHCP server may be unavailable, enabling devices to communicate locally even without a configured IP address. However, devices using APIPA cannot communicate with devices outside their local network, as these addresses are not routable on the internet. Understanding the circumstances under which APIPA is used and its limitations is essential for troubleshooting connectivity issues in network environments.
- Extended unique identifier (EUI-64)
Extended Unique Identifier (EUI-64) is a standard for creating unique 64-bit identifiers for network interfaces, particularly in IPv6 addressing. EUI-64 is derived from a device’s MAC (Media Access Control) address, which is typically 48 bits long. To convert a MAC address to an EUI-64 format, the process involves inserting a fixed 16-bit value in the middle and flipping the seventh bit of the first byte.
For the exam, you should know that EUI-64 allows devices to automatically generate their own IPv6 addresses by appending the EUI-64 identifier to the network prefix. This process simplifies address configuration and ensures uniqueness across devices in a network. Understanding the significance of EUI-64 in IPv6 addressing, its creation process from MAC addresses, and its role in Stateless Address Autoconfiguration (SLAAC) is important for comprehending IPv6 networking and addressing schemes.
- Multicast
Multicast is a method of data transmission where information is sent from one source to multiple destinations simultaneously. Unlike unicast, which sends data to a single recipient, or broadcast, which sends data to all devices in a network, multicast allows for efficient use of network resources by sending a single copy of the data to a specified group of interested receivers.
For the exam, you should know that multicast uses specific IP address ranges, typically from 224.0.0.0 to 239.255.255.255 in IPv4. It is commonly used in applications such as video conferencing, streaming media, and online gaming, where data needs to be delivered to multiple users at once. Understanding multicast addressing, the role of multicast groups, and how protocols like Internet Group Management Protocol (IGMP) manage multicast traffic is essential for effective network design and resource management.
- Unicast
Unicast is a method of data transmission where information is sent from one sender to one specific recipient over a network. This one-to-one communication ensures that the data packets are directed to a single device’s unique IP address, making it the most common form of data transfer used in various applications, including web browsing, file transfers, and email.
For the exam, you should know that unicast communication is characterized by its direct, dedicated nature, which can lead to increased bandwidth consumption when multiple devices request the same data, as each device requires its own separate stream. Understanding the concept of unicast, its advantages in straightforward communication, and its limitations in terms of scalability and efficiency in high-demand scenarios is important for effective network design and performance optimization.
- Anycast
Anycast is a network addressing and routing method in which data is sent from a source to the nearest or best destination within a group of potential receivers that share the same IP address. In an anycast setup, multiple devices (usually servers) can share the same IP address, and the network routes the data to the closest or most optimal server based on routing metrics.
For the exam, you should know that anycast is commonly used in content delivery networks (CDNs) and DNS services to improve response times and load balancing. It enhances redundancy and resilience, as traffic can be automatically rerouted to another server in the event of a failure. Understanding how anycast differs from unicast and multicast, along with its applications and benefits in network design, is crucial for optimizing performance and resource utilization in distributed systems.
- Broadcast
Broadcast is a method of data transmission where a message is sent from one sender to all devices in a network segment. In a broadcast, the data packets are sent to a special broadcast address that all devices on the local network recognize and process. This means every device receives the broadcast message, regardless of whether it is the intended recipient.
For the exam, you should know that broadcast communication is commonly used in local area networks (LANs) for tasks such as address resolution protocol (ARP) requests and network discovery. However, broadcast traffic can lead to network congestion if overused, as every device must process the incoming packets. Understanding the implications of broadcast communication, its uses, and its limitations in larger or segmented networks is essential for effective network management and design.
- Link local
Link-local addresses are IP addresses that are automatically assigned to network interfaces for communication within a single local network segment. In IPv4, link-local addresses range from 169.254.0.0 to 169.254.255.255 (commonly used in APIPA). In IPv6, link-local addresses always start with the prefix fe80::/10. These addresses are used when a device cannot obtain an IP address through DHCP or other means but still needs to communicate with other devices on the same local network.
For the exam, you should know that link-local addresses are only valid within the local network segment and are not routable beyond it, meaning they cannot be used for communication across different networks. Understanding how link-local addressing works, especially in the context of troubleshooting network connectivity issues and identifying automatic address assignment processes, is important for managing both IPv4 and IPv6 networks.
Loopback
Loopback refers to a special network interface that allows a device to send and receive data to and from itself. The loopback address in IPv4 is 127.0.0.1, and in IPv6, it is represented as ::1. This interface is commonly used for testing and troubleshooting purposes, as it enables software applications and network configurations to be validated without needing to send traffic over a physical network.
For the exam, you should know that loopback addresses are essential for diagnosing network issues, testing server applications, and verifying that the TCP/IP stack is functioning correctly. Understanding how loopback interfaces operate and their significance in network diagnostics is crucial for effective network management and troubleshooting.
- Default gateway
A default gateway is a network node that serves as an access point or router for devices on a local network to communicate with external networks, such as the internet. It is the IP address of the router or device that traffic is sent to when a device does not have a specific route for a destination IP address. Typically, devices on the same local network segment will have the same default gateway address.
For the exam, you should know that configuring a default gateway is essential for enabling communication between local devices and external networks. Without a correctly set default gateway, devices can only communicate with others on the same local network and cannot access resources outside of it. Understanding how to identify, configure, and troubleshoot default gateway settings is vital for effective network connectivity and management.
Classless (variable-length
subnet mask)
Classless Inter-Domain Routing (CIDR), often associated with variable-length subnet masking (VLSM), is a method for allocating IP addresses and managing network routing more efficiently than the traditional class-based system. CIDR allows for flexible subnetting by permitting subnet masks of varying lengths, which means network administrators can create subnets of different sizes based on actual needs rather than being restricted to fixed classful boundaries (Class A, B, or C).
For the exam, you should know that CIDR is represented in notation using the IP address followed by a slash and the subnet mask length (e.g., 192.168.1.0/24). This flexibility in subnetting improves address space utilization and reduces waste of IP addresses. Understanding CIDR and VLSM is crucial for designing scalable networks, optimizing routing tables, and efficiently managing IP address allocations across various network segments.
Classful IPv4 Subnetting - A
Classful addressing is a method of allocating IP addresses based on predefined classes that dictate how the address space is divided among networks. Class A is one of these classes, designated for large networks. It uses the first octet (8 bits) for network identification and the remaining three octets (24 bits) for host identification, allowing for over 16 million possible host addresses within a single Class A network.
For the exam, you should know that Class A addresses range from 1.0.0.0 to 126.0.0.0. The first bit of a Class A address is always set to 0, which identifies it as a Class A address. Class A is primarily used by very large organizations or service providers that need to assign a vast number of IP addresses to devices within a single network. Understanding the structure of Class A addresses, their range, and their application in network design is important for grasping the fundamentals of IP addressing.
Classful IPv4 Subnetting - B
Classful addressing defines a structure for IP addresses, and Class B is one of the primary classes used to allocate IP space. Class B addresses are designed for medium to large networks, utilizing the first two octets (16 bits) for network identification and the remaining two octets (16 bits) for host identification. This allows for up to 65,536 possible hosts within a single Class B network.
For the exam, you should know that Class B addresses range from 128.0.0.0 to 191.255.255.255. The first two bits of a Class B address are set to “10,” which distinguishes it from other classes. Class B is typically used by organizations that require a significant number of IP addresses but do not need as many as a Class A network provides. Understanding the structure, range, and application of Class B addresses is essential for effective IP address management and network design.
