Advanced Domain 1: Networking Fundamentals

Question 1

Card 1
Question:
A network engineer needs to implement a highly available network design for critical applications. Which routing protocol feature ensures alternate paths are quickly used in case of a primary link failure?
Administrative Distance
Route Summarization
Equal-Cost Multi-Path (ECMP)
BGP Route Reflectors
OSPF Stub Areas

Answer 1

Correct Answer:
3. Equal-Cost Multi-Path (ECMP)
Explanation:
ECMP allows the use of multiple best paths for routing, ensuring redundancy and load balancing. If one path fails, traffic is rerouted to another available path without significant delay.
Practical Use:
Data centers use ECMP to distribute traffic across redundant links to enhance both reliability and throughput.
Why Others Are Incorrect:
Administrative Distance: Defines trustworthiness of routing protocols, not failover capabilities.
Route Summarization: Reduces routing table size but does not address failover.
BGP Route Reflectors: Improve BGP scalability, not redundancy for paths.
OSPF Stub Areas: Optimize OSPF by limiting routes but don’t provide path redundancy.
Exam Objective Reference:
Domain 1.3: Compare and contrast characteristics of routing protocols.
Follow-Up Question:
How does ECMP differ from fast reroute mechanisms in link-state routing protocols?

Question 2

Question:
In an IPv6 network, what mechanism ensures that a device can automatically generate its own IP address without requiring a DHCP server?
Stateless Address Autoconfiguration (SLAAC)
DHCPv6 Lite
Neighbor Discovery Protocol (NDP)
Router Advertisements (RA)
Link-Local Addressing

Answer 2

Correct Answer:
1. Stateless Address Autoconfiguration (SLAAC)
Explanation:
SLAAC allows devices to configure their IPv6 addresses autonomously using information from Router Advertisements, making deployment more straightforward.
Practical Use:
IoT networks often use SLAAC to minimize manual configuration and improve scalability.
Why Others Are Incorrect:
DHCPv6 Lite: Not a standard feature in IPv6.
Neighbor Discovery Protocol (NDP): Used for address resolution and discovery but doesn’t assign IPs.
Router Advertisements (RA): Facilitate SLAAC but are not the mechanism itself.
Link-Local Addressing: Automatically generated but limited to communication within the same link.
Exam Objective Reference:
Domain 1.5: Compare IPv6 concepts and implementation.
Follow-Up Question:
What are the benefits and limitations of using SLAAC compared to DHCPv6 in enterprise networks?

Question 3

Question:
An enterprise needs to implement VLAN trunking over a high-speed link. Which protocol ensures compatibility across vendor devices?
ISL (Inter-Switch Link)
802.1Q
VTP (VLAN Trunking Protocol)
LLDP (Link Layer Discovery Protocol)
CDP (Cisco Discovery Protocol)

Answer 3

Correct Answer:
2. 802.1Q
Explanation:
The IEEE 802.1Q standard is an open protocol for VLAN tagging, ensuring interoperability between devices from different manufacturers.
Practical Use:
Organizations with mixed vendor environments use 802.1Q to maintain seamless VLAN communication across switches.
Why Others Are Incorrect:
ISL (Inter-Switch Link): Cisco-proprietary and not interoperable.
VTP: Used for VLAN management, not trunking.
LLDP: Discovers network topology but does not handle VLAN tagging.
CDP: Cisco-specific protocol for topology discovery.
Exam Objective Reference:
Domain 1.7: Explain VLAN and trunking concepts.
Follow-Up Question:
What challenges might arise when integrating older Cisco devices using ISL into a modern 802.1Q-based network?

Question 4

Question:
Which protocol allows a Layer 2 device to prevent loops in a network topology by blocking redundant links?
Rapid Spanning Tree Protocol (RSTP)
LACP (Link Aggregation Control Protocol)
MSTP (Multiple Spanning Tree Protocol)
STP (Spanning Tree Protocol)
TRILL (Transparent Interconnection of Lots of Links)

Answer 4

Correct Answer:
1. Rapid Spanning Tree Protocol (RSTP)
Explanation:
RSTP, an evolution of STP, rapidly converges the network after a topology change by quickly transitioning ports to forwarding or blocking states.
Practical Use:
RSTP is commonly implemented in enterprise networks to minimize downtime during link failures.
Why Others Are Incorrect:
LACP: Bundles links but doesn’t address loops.
MSTP: A multi-instance version of STP but slower than RSTP.
STP: Slower convergence compared to RSTP.
TRILL: Provides loop-free topology but operates differently from RSTP.
Exam Objective Reference:
Domain 1.6: Summarize Layer 2 concepts.
Follow-Up Question:
How does RSTP handle topology changes compared to the original STP?

Question 5

Question:
An engineer is tasked with minimizing broadcast traffic in a flat Layer 2 network. Which advanced feature of modern switches helps to partition the network logically?
VLANs
MAC Filtering
Port Mirroring
Flow Control
802.3ad Link Aggregation

Answer 5

Correct Answer:
1. VLANs
Explanation:
VLANs create logical network segments within a physical switch, reducing broadcast domains and enhancing security and performance.
Practical Use:
Large corporate networks often segment departments like HR and Finance into separate VLANs to ensure isolation and reduce congestion.
Why Others Are Incorrect:
MAC Filtering: Controls access based on MAC addresses but doesn’t affect broadcast traffic.
Port Mirroring: Duplicates traffic for monitoring but doesn’t logically segment the network.
Flow Control: Manages congestion but doesn’t partition the network.
802.3ad Link Aggregation: Combines links for increased bandwidth but doesn’t address broadcast domains.
Exam Objective Reference:
Domain 1.2: Compare and contrast physical network topologies.
Follow-Up Question:
What potential challenges might arise when managing VLAN configurations across multiple switches?

Question 6

What advanced feature of IPv6 allows devices to determine their next-hop neighbor without broadcasting ARP requests, improving efficiency?
SLAAC
Neighbor Discovery Protocol (NDP)
Router Solicitation
DHCPv6
IPv6 Path MTU Discovery

Answer 6

Correct Answer:
2. Neighbor Discovery Protocol (NDP)
Explanation:
NDP uses ICMPv6 messages to handle tasks such as discovering next-hop addresses, managing address resolution, and determining link-layer addresses, replacing ARP in IPv6.
Practical Use:
Networks with high IPv6 adoption use NDP to optimize neighbor discovery processes and reduce broadcast-like behavior seen in IPv4 with ARP.
Why Others Are Incorrect:
SLAAC: Provides address autoconfiguration but doesn’t address neighbor discovery.
Router Solicitation: Requests Router Advertisements, part of NDP but not the full mechanism.
DHCPv6: Manages address assignment but doesn’t handle neighbor discovery.
IPv6 Path MTU Discovery: Determines the MTU for a path, unrelated to neighbor resolution.
Exam Objective Reference:
Domain 1.5: Compare IPv6 concepts and implementation.
Follow-Up Question:
How does NDP handle neighbor reachability compared to IPv4’s ARP?

Question 7

Question:
An enterprise has a multi-VLAN setup. Which protocol dynamically distributes VLAN information across all connected switches to ensure consistency?
VTP (VLAN Trunking Protocol)
802.1Q
ISL (Inter-Switch Link)
MSTP
STP

Answer 7

Correct Answer:
1. VTP (VLAN Trunking Protocol)
Explanation:
VTP simplifies VLAN management by propagating VLAN configurations across connected switches, reducing manual configuration errors in large networks.
Practical Use:
Enterprises with extensive VLANs use VTP to maintain consistency across interconnected switches, particularly in data center environments.
Why Others Are Incorrect:
802.1Q: Handles VLAN tagging but doesn’t propagate VLAN information.
ISL: Cisco-proprietary tagging protocol, now largely obsolete.
MSTP: Manages spanning tree instances but not VLAN distribution.
STP: Prevents Layer 2 loops but doesn’t distribute VLAN information.
Exam Objective Reference:
Domain 1.7: Explain VLAN and trunking concepts.
Follow-Up Question:
What are the potential risks of using VTP in a large network, and how can they be mitigated?

Question 8

Question:
Which IPv4 address type is used for communication between devices that do not need global uniqueness and operate only within a private network?
Public Address
Private Address
APIPA
Multicast Address
Reserved Address

Answer 8

Correct Answer:
2. Private Address
Explanation:
Private IPv4 addresses are reserved for internal use within private networks and cannot be routed on the public internet, ensuring security and address conservation.
Practical Use:
Businesses commonly use private IP ranges (e.g., 192.168.0.0/16) for LAN configurations while relying on NAT for external connectivity.
Why Others Are Incorrect:
Public Address: Routable on the internet, unsuitable for internal-only communication.
APIPA: Used for link-local addressing when DHCP fails, not for structured private networks.
Multicast Address: Targets multiple devices simultaneously but is not private.
Reserved Address: Reserved for special purposes and not assigned for general private use.
Exam Objective Reference:
Domain 1.3: Explain IPv4 addressing schemes.
Follow-Up Question:
How does the use of NAT affect the visibility and security of devices using private addresses?

Question 9

Question:
What Layer 2 protocol can be used to bond multiple physical interfaces into a single logical link to increase bandwidth and provide redundancy?
LACP (Link Aggregation Control Protocol)
STP (Spanning Tree Protocol)
CDP (Cisco Discovery Protocol)
RSTP
EIGRP

Answer 9

Correct Answer:
1. LACP (Link Aggregation Control Protocol)
Explanation:
LACP is part of IEEE 802.3ad and enables the bundling of multiple physical links into a logical interface for load balancing and fault tolerance.
Practical Use:
Data centers and enterprises use LACP to optimize bandwidth utilization between switches or servers.
Why Others Are Incorrect:
STP: Prevents loops in Layer 2 networks but doesn’t aggregate links.
CDP: Cisco-proprietary protocol for device discovery, unrelated to link aggregation.
RSTP: Accelerates spanning tree convergence but doesn’t aggregate links.
EIGRP: A Layer 3 routing protocol, not relevant to Layer 2 link aggregation.
Exam Objective Reference:
Domain 1.6: Summarize Layer 2 concepts.
Follow-Up Question:
What happens to traffic if one of the physical links in an LACP bundle fails?

Question 10

Question:
Which multicast protocol efficiently manages group membership information for hosts and routers in a network?
IGMP (Internet Group Management Protocol)
OSPF (Open Shortest Path First)
PIM (Protocol Independent Multicast)
RIP (Routing Information Protocol)
MPLS (Multiprotocol Label Switching)

Answer 10

Correct Answer:
1. IGMP (Internet Group Management Protocol)
Explanation:
IGMP enables routers to discover which hosts are members of a specific multicast group, ensuring efficient multicast delivery.
Practical Use:
Streaming services and IPTV networks use IGMP to manage multicast group memberships for efficient data distribution.
Why Others Are Incorrect:
OSPF: A link-state routing protocol, not for multicast group management.
PIM: Routes multicast traffic but relies on IGMP for group membership information.
RIP: Distance-vector routing protocol, unrelated to multicast.
MPLS: Directs data based on labels, unrelated to multicast group membership.
Exam Objective Reference:
Domain 1.3: Explain characteristics of multicast.
Follow-Up Question:
How does IGMP snooping enhance multicast performance in a switched network?

Question 11

Question:
What technology allows Ethernet frames to traverse non-Ethernet networks while preserving Layer 2 information?
Frame Relay
GRE Tunneling
MPLS
Ethernet over MPLS (EoMPLS)
L2TP

Answer 11

Correct Answer:
4. Ethernet over MPLS (EoMPLS)
Explanation:
EoMPLS encapsulates Ethernet frames within MPLS labels, enabling Layer 2 traffic to be transmitted across WANs while retaining VLAN information.
Practical Use:
Enterprises use EoMPLS to connect remote offices over a service provider’s MPLS network without losing Layer 2 configuration.
Why Others Are Incorrect:
Frame Relay: Legacy WAN technology, not suited for Layer 2 Ethernet.
GRE Tunneling: Provides encapsulation but lacks VLAN preservation.
MPLS: Facilitates Layer 3 traffic but doesn’t encapsulate Ethernet.
L2TP: Focuses on VPN tunneling, not Ethernet frames.
Exam Objective Reference:
Domain 1.6: Explain characteristics of Layer 2 and Layer 3 protocols.
Follow-Up Question:
How does EoMPLS differ from VXLAN in extending Layer 2 networks?

Question 12

Question:
In a multi-VLAN environment, which protocol ensures that a single multicast stream is distributed only to the VLANs requiring it?
IGMP Snooping
PIM-SM
MLD
Multicast VLAN Registration (MVR)
MSDP

Answer 12

Correct Answer:
4. Multicast VLAN Registration (MVR)
Explanation:
MVR allows multicast streams to be delivered only to subscribed VLANs, reducing unnecessary traffic in multi-VLAN environments.
Practical Use:
MVR is often deployed in IPTV networks to deliver multicast streams efficiently to specific customer VLANs.
Why Others Are Incorrect:
IGMP Snooping: Manages multicast at Layer 2 but lacks VLAN-specific stream management.
PIM-SM: Handles multicast routing but doesn’t manage VLAN distribution.
MLD: Multicast Listener Discovery is for IPv6, not VLAN-specific.
MSDP: Shares multicast sources between routers, unrelated to VLANs.
Exam Objective Reference:
Domain 1.7: Summarize multicast concepts in VLANs.
Follow-Up Question:
What are the challenges of implementing MVR in a large-scale IPTV network

Question 13

Question:
Which feature of IPv6 eliminates the need for NAT, simplifying direct device-to-device communication?
Stateless Address Autoconfiguration
Unique Local Addresses
Global Unicast Addresses
Site-Local Addresses
IPv6 Anycast

Answer 13

Correct Answer:
3. Global Unicast Addresses
Explanation:
IPv6 Global Unicast Addresses are globally unique and routable on the internet, removing the need for NAT and enabling end-to-end communication.
Practical Use:
IoT networks benefit from global unicast addressing for direct communication with devices without intermediate address translation.
Why Others Are Incorrect:
Stateless Address Autoconfiguration: Configures IPs but doesn’t replace NAT.
Unique Local Addresses: Not routable on the global internet.
Site-Local Addresses: Deprecated in favor of unique local addresses.
IPv6 Anycast: Routes traffic to the nearest device in a group, not suitable for global communication.
Exam Objective Reference:
Domain 1.5: Compare IPv6 concepts and implementation.
Follow-Up Question:
What are the primary security considerations when using Global Unicast Addresses in an IPv6 network?

Question 14

Question:
In an enterprise network, which feature of link-state routing protocols like OSPF ensures network stability during frequent topology changes?
LSA Throttling
Route Aggregation
Split Horizon
Passive Interface
Route Redistribution

Answer 14

Correct Answer:
1. LSA Throttling
Explanation:
LSA Throttling limits the frequency of Link-State Advertisement (LSA) updates, ensuring that network resources are conserved and instability is reduced during frequent changes.
Practical Use:
LSA Throttling is critical in large enterprise networks where frequent topology changes can otherwise lead to excessive flooding and CPU load.
Why Others Are Incorrect:
Route Aggregation: Summarizes routes but does not affect LSA behavior.
Split Horizon: Prevents routing loops in distance-vector protocols, not applicable to link-state protocols.
Passive Interface: Disables route advertisements but does not stabilize LSAs.
Route Redistribution: Shares routes between protocols but does not control LSA flooding.
Exam Objective Reference:
Domain 1.3: Compare and contrast characteristics of routing protocols.
Follow-Up Question:
What additional mechanisms can OSPF use to handle route flapping in unstable networks?

Question 15

Question:
Which feature in modern Layer 3 switches allows for efficient inter-VLAN routing by avoiding traditional router hops?
VLAN Trunking
SVI (Switch Virtual Interface)
LACP
DHCP Snooping
Proxy ARP

Answer 15

Correct Answer:
2. SVI (Switch Virtual Interface)
Explanation:
An SVI provides Layer 3 functionality on a Layer 2 switch, enabling routing between VLANs directly within the switch without requiring an external router.
Practical Use:
SVIs are widely used in campus networks for scalable and efficient inter-VLAN communication.
Why Others Are Incorrect:
VLAN Trunking: Allows multiple VLANs on a single link but does not perform routing.
LACP: Bundles links but is unrelated to VLAN routing.
DHCP Snooping: Secures DHCP traffic but does not handle inter-VLAN routing.
Proxy ARP: Resolves ARP requests but does not provide routing functionality.
Exam Objective Reference:
Domain 1.7: Explain VLAN and trunking concepts.
Follow-Up Question:
How does the use of SVIs impact the performance of inter-VLAN traffic compared to traditional routing?