Address Allocation Flashcards
What is ARP used for in address allocation?
ARP is used to resolve IP addresses to MAC addresses
Why is it a bad sign if you receive an ARP response unexpectedly?
It indicates a duplicate or misconfigured IP address
Why should static IP allocation be minimized?
Static allocation increases the risk of errors and management difficulties
What devices typically require static IP addresses?
Routers and critical infrastructure devices need static IP addresses
Why must devices with static IPs be clearly labeled?
To prevent IP conflicts and ensure proper network management by avoiding accidental reuse or misconfiguration.
What is DHCP?
Dynamic Host Configuration Protocol automates IP address assignment
Why is DHCP preferable to static allocation?
It simplifies management and prevents address conflicts
How does DHCP work?
It dynamically assigns IP addresses as devices join the network
What happens if a DHCP server goes down?
Devices without batteries lose their addresses and may reboot
Why is static DHCP not recommended for large networks?
It is difficult to manage and prone to failure if servers go down
What is the typical behavior of home routers regarding DHCP leases?
Home routers do not record leases and may reassign duplicate IPs
What are common solutions for DHCP redundancy?
Two servers managing different pools or one with failover capability
Why is having multiple DHCP servers a potential problem?
More servers increase complexity and potential points of failure
What is DHCP relaying?
A mechanism to forward DHCP requests to a central server
How do DHCP relays operate?
They forward packets deterministically without storing state
What is a rogue DHCP server?
An unauthorized server that disrupts network configuration
Why are rogue DHCP servers dangerous?
They can redirect traffic by altering router information
How is the risk of rogue DHCP servers mitigated today?
Encryption reduces the threat of traffic redirection
What is the role of Ethernet MAC addresses in networking?
They uniquely identify devices at the hardware level
How are Ethernet MAC addresses structured?
Three bytes identify the manufacturer and three bytes identify the device
Can MAC addresses be changed?
Yes they can be changed for compatibility or malicious purposes
What is SLAAC?
Stateless Address Auto Configuration assigns IPv6 addresses automatically
What is the main privacy concern with SLAAC?
It embeds the MAC address in the IPv6 address allowing tracking
How does RFC4941 improve SLAAC privacy?
It generates random IPv6 addresses that change periodically
What is RFC7217 and how does it differ from RFC4941?
RFC7217 creates stable IPv6 addresses consistent on the same network
What is the purpose of IPv6 router advertisements?
They announce network information to devices
What are the M and O flags in IPv6 DHCP?
M indicates managed mode and O provides additional configuration
Why is DHCPv6 logging debated?
It is easier to forge addresses reducing accountability
What happens if a device receives a duplicate IP?
It may fail to connect unless duplicate detection mechanisms are in place
Why is SLAAC not suitable for DNS configuration by default?
SLAAC does not provide DNS server information directly
What is the main advantage of SLAAC over DHCP?
SLAAC eliminates the need for a central server
How does DHCPDISCOVER initiate the DHCP process?
It broadcasts a request for an IP address
What does DHCPOFFER provide during the DHCP process?
A server offers an IP address along with lease details
What is the purpose of DHCPACK in the process?
It confirms the lease and finalizes the IP assignment
Why is DHCP unauthenticated a security risk?
It allows unauthorized servers to tamper with network settings
What is the effect of short lease times in DHCP?
They reduce conflicts after server restarts
How do DHCP relays benefit large networks?
They centralize management and distribute requests
What is a critical challenge with multiple DHCP servers?
Ensuring synchronization to prevent IP conflicts
Why is DHCP essential for large dynamic networks?
It automates address allocation and reduces errors
What happens during DHCP renewal?
A device requests to extend its current lease
What is the impact of DHCP server failure on devices with batteries?
They retain their IP addresses until the lease expires
Why is DHCP redundancy critical for reliability?
It ensures continuity during server outages
What is a key limitation of unmanaged DHCP relays?
They rely entirely on central servers for decisions
What is the purpose of RFC1918 addresses?
To provide private address spaces for local networks
What is the main difference between SLAAC and DHCPv6?
SLAAC self-assigns addresses while DHCPv6 is managed by a server
How do privacy extensions in IPv6 work?
They generate temporary addresses to prevent tracking
What are the challenges of using privacy addresses for administrators?
Frequent changes make tracking and logging difficult
Why do stable addresses improve IPv6 logging?
They remain consistent on the same network
What is the purpose of router advertisements in IPv6?
To announce connectivity and network details
How is SLAAC configured in IPv6?
Devices deduce the prefix and generate their own addresses
Why is the MAC-based addressing in SLAAC a privacy concern?
It exposes the hardware identity across networks
How does RFC4941 address IPv6 privacy concerns?
It uses random suffixes to generate temporary addresses
What is the difference between RFC4941 and RFC7217?
RFC4941 creates random addresses while RFC7217 uses stable ones
Why is redundancy not always beneficial for DHCP servers?
More servers increase complexity and failure points
What is the purpose of a relay in DHCP?
To forward requests to a centralized server
What is the risk of DHCP spoofing?
Attackers can manipulate routing and DNS information
What is SLAAC’s limitation regarding DNS servers?
It does not natively provide DNS configuration
Why is dual-stack IPv4 and IPv6 necessary?
IPv6 deployment is incomplete requiring fallback to IPv4
What does DHCPREQUEST do in the process?
It lets a client confirm or renew an offered IP address
How does VMware handle DHCP in modern networks?
It uses a virtual server with failover for reliability
What is the role of timeouts in DHCP?
To release unused addresses and prevent conflicts
What is the benefit of DHCP over static allocation?
It dynamically manages addresses reducing conflicts
Why is DHCP failure considered critical?
It can disrupt the entire network by failing to assign addresses
How does SLAAC simplify IPv6 address allocation?
It eliminates the need for a DHCP server
What is the challenge with privacy extensions in IPv6?
They make tracking and debugging harder
How does DHCPACK handle duplicate IPs?
It ensures only one device receives the assigned IP
What are the risks of unmanaged DHCP servers?
They can assign conflicting or incorrect addresses
Why is SLAAC preferred for simple IPv6 networks?
It requires no central management for address assignment
What is a major security concern with DHCP?
It allows unauthorized devices to disrupt network operations
