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Question 101

Which protocol resolves IPv6 neighbors using multicast discovery?

1. ICMPv6 Neighbor Discovery
2. IPv4 ARP
3. BOOTP relay
4. Ethernet pause

Correct Answer: 1

Explanation:

IPv6 does not use ARP for resolving neighboring devices. Instead, IPv6 uses Neighbor Discovery Protocol, which operates through ICMPv6 messages. Neighbor Discovery provides several functions, including address resolution, router discovery, prefix discovery, and neighbor reachability detection. Devices exchange Neighbor Solicitation and Neighbor Advertisement messages to discover and communicate with neighboring IPv6 nodes. Multicast addresses are used extensively to make this process efficient. IPv4 ARP has a similar address-resolution purpose but belongs to IPv4 networking. Therefore, ICMPv6 Neighbor Discovery is the correct answer because it provides the IPv6 mechanism for discovering and resolving neighboring devices.

Question 102

Which Ethernet feature distributes traffic across multiple physical links?

1. Port mirroring
2. Link aggregation
3. Storm control
4. MAC learning

Correct Answer: 2

Explanation:

Link aggregation combines multiple physical Ethernet interfaces into a logical connection. Traffic can then be distributed across the participating physical links according to the device’s hashing and forwarding behavior. This provides increased aggregate bandwidth and redundancy compared with relying on a single physical connection. Port mirroring copies traffic for monitoring purposes, storm control limits excessive broadcast or multicast traffic, and MAC learning builds forwarding information from observed source addresses. Link aggregation is therefore the appropriate technology when several physical interfaces need to operate together as a logical connection while improving available capacity and resilience.

Question 103

Which IPv6 address type identifies a single interface?

1. Multicast
2. Anycast
3. Unicast
4. Broadcast

Correct Answer: 3

Explanation:

An IPv6 unicast address identifies a single interface and is used when communication is intended for one specific destination. IPv6 supports several address categories, including unicast, multicast, and anycast. Unlike IPv4, IPv6 does not use traditional broadcast addressing. Multicast addresses identify a group of interfaces, while anycast addresses can identify multiple interfaces where traffic is delivered to the appropriate nearest destination according to routing. Therefore, unicast is the correct answer because it represents communication toward an individual IPv6 interface rather than a group or broadcast-style destination.

Question 104

Which mechanism limits excessive broadcast traffic on switches?

1. MAC authentication
2. Storm control
3. Packet capture
4. Route filtering

Correct Answer: 2

Explanation:

Storm control is designed to limit excessive amounts of broadcast, multicast, or unknown-unicast traffic entering a switching interface. A traffic storm can consume significant network resources and potentially affect normal forwarding operations. Storm-control mechanisms allow administrators to establish thresholds so that excessive traffic can be controlled according to configured behavior. MAC authentication addresses access control, packet capture assists troubleshooting and analysis, and route filtering controls routing information rather than Layer 2 traffic storms. Therefore, storm control is the correct answer because it specifically protects switched networks against excessive Layer 2 traffic conditions.

Question 105

Which protocol dynamically assigns IPv4 host configuration parameters?

1. DHCP
2. FTP
3. TFTP
4. Telnet

Correct Answer: 1

Explanation:

Dynamic Host Configuration Protocol, or DHCP, automatically provides hosts with network configuration information. Typical DHCP information can include an IPv4 address, subnet mask, default gateway, and DNS server information. This reduces manual configuration requirements and makes address management easier in larger environments. FTP is designed for file transfers, TFTP provides a lightweight file-transfer mechanism, and Telnet provides remote terminal access. DHCP therefore matches the requirement because it dynamically supplies IPv4 configuration information to clients. Network administrators can also configure DHCP reservations or pools depending on the platform and operational requirements.

Question 106

Which switch database records learned source MAC addresses?

1. Routing information base
2. Forwarding database
3. Neighbor cache
4. Resolver database

Correct Answer: 2

Explanation:

A switch forwarding database records learned MAC addresses and associates them with specific Layer 2 interfaces. When an Ethernet frame arrives, the switch examines its source MAC address and can learn where that address is reachable. Later, destination MAC information can be used to determine the appropriate outgoing interface. This process helps switches forward frames efficiently rather than flooding every frame across all available ports. A routing information base contains Layer 3 routing information, while neighbor and resolver databases serve different networking purposes. Therefore, the forwarding database is the correct answer for learned MAC-address information.

Question 107

Which IPv4 protocol maps addresses to hardware identifiers?

1. ICMP
2. ARP
3. GRE
4. PPP

Correct Answer: 2

Explanation:

Address Resolution Protocol, or ARP, maps an IPv4 address to the corresponding MAC address on a local Layer 2 network. When a device knows the destination IPv4 address but does not know the associated hardware address, it can use ARP to discover that information. The requesting host sends an ARP request, and the device owning the address can respond with its MAC address. ICMP supports diagnostic and control messaging, GRE provides tunneling, and PPP provides point-to-point communication. Therefore, ARP is the correct answer because it performs IPv4-to-MAC address resolution.

Question 108

Which feature provides centralized authentication for network administrators?

1. RADIUS
2. VLAN tagging
3. Ethernet OAM
4. Packet sampling

Correct Answer: 1

Explanation:

RADIUS is commonly used to provide centralized authentication, authorization, and accounting services for network access and administrative environments. Instead of maintaining independent credentials on every device, organizations can use a centralized authentication server to validate users and apply appropriate access policies. This improves administrative consistency and can simplify account management across many network devices. VLAN tagging identifies logical Layer 2 networks, Ethernet OAM provides operational and maintenance capabilities, and packet sampling collects traffic statistics. Therefore, RADIUS is the correct answer because it provides a standardized centralized framework for authentication and related access-management functions.

Question 109

Which Junos feature groups interfaces into logical security zones?

1. Firewall filters
2. Security zones
3. Routing policies
4. Classifiers

Correct Answer: 2

Explanation:

Security zones logically group interfaces and establish a foundation for applying security policies between different network segments. In Juniper security platforms, zones help administrators organize interfaces according to their security role and control traffic between zones through appropriate policies. Firewall filters can apply packet-processing rules, routing policies influence route acceptance or advertisement, and classifiers identify traffic characteristics for forwarding or service treatment. Security zones therefore directly match the requirement of grouping interfaces into logical security domains. Their organization provides an important structural element for implementing stateful security controls on supported Juniper platforms.

Question 110

Which IPv4 mechanism tests whether a destination is reachable?

1. ICMP Echo
2. DHCP Discover
3. DNS Query
4. ARP Probe

Correct Answer: 1

Explanation:

ICMP Echo messages are commonly used to test IP reachability between network devices. The source sends an Echo Request toward the destination, and if the destination is reachable and configured to respond, it returns an Echo Reply. Tools such as ping use this mechanism to provide basic connectivity testing and response-time information. DHCP Discover is used to locate DHCP servers, DNS queries resolve names, and ARP probes have local address-resolution or duplicate-address detection purposes. Therefore, ICMP Echo is the correct answer because it directly supports the standard reachability test commonly performed with ping.

Question 111

Which VLAN protocol carries multiple VLANs across trunk links?

1. 802.1Q
2. PPPoE
3. HDLC
4. L2TP

Correct Answer: 1

Explanation:

IEEE 802.1Q provides VLAN tagging for Ethernet frames and allows multiple logical VLANs to traverse a shared trunk connection. A VLAN tag identifies the logical VLAN associated with the frame, allowing switches on different sides of the trunk to maintain separation between broadcast domains. PPPoE is commonly associated with subscriber access, HDLC is a point-to-point data-link protocol, and L2TP is a tunneling protocol. Therefore, 802.1Q is the correct answer because VLAN tagging enables multiple VLANs to share an Ethernet trunk while preserving their logical separation.

Question 112

Which routing policy action rejects a matching route?

1. Accept
2. Reject
3. Modify
4. Resolve

Correct Answer: 2

Explanation:

A routing policy can use a reject action to prevent a matching route from being accepted or propagated according to the policy context. Routing policies are important tools in Junos because they allow administrators to control how routing information is imported, exported, modified, or evaluated. An accept action permits a matching route to continue through the relevant policy process, while modification actions can change attributes or other routing properties. Resolve is associated with next-hop resolution concepts rather than directly rejecting a route. Therefore, reject is the correct action when a matching route must be denied.

Question 113

Which interface type represents a logical Layer 3 connection?

1. Physical Ethernet
2. Aggregated Ethernet
3. Loopback interface
4. Console port

Correct Answer: 3

Explanation:

A loopback interface is a logical interface that does not depend on a particular physical network link remaining operational. It can provide a stable Layer 3 address for management, routing protocols, device identification, or other services. Because it is logical, the loopback interface remains available as long as the device’s routing and interface configuration maintain it. Physical Ethernet represents a hardware interface, aggregated Ethernet combines multiple physical links, and a console port is intended for device management access. Therefore, a loopback interface is the correct answer for a logical Layer 3 connection.

Question 114

Which mechanism provides traffic classification for differentiated forwarding?

1. CoS
2. ARP
3. LLDP
4. DHCP

Correct Answer: 1

Explanation:

Class of Service, commonly abbreviated as CoS, provides mechanisms for classifying and treating network traffic according to configured forwarding requirements. Different traffic classes can receive different queuing, scheduling, marking, or congestion-management behavior depending on platform capabilities and configuration. This can help organizations prioritize traffic that has particular performance requirements. ARP handles IPv4 address resolution, LLDP discovers directly connected devices, and DHCP supplies host configuration parameters. Therefore, CoS is the correct answer because it provides the framework for classifying traffic and applying differentiated forwarding treatment within the network.

Question 115

Which IPv6 address begins with the link-local prefix?

1. 2001:db8::/32
2. fe80::/10
3. ff00::/8
4. fc00::/7

Correct Answer: 2

Explanation:

The IPv6 prefix fe80::/10 identifies link-local addresses. These addresses are intended for communication on the local link and are not normally routed between different IPv6 networks. IPv6-enabled interfaces commonly use link-local addresses for functions such as neighbor discovery and certain routing-protocol communications. The 2001:db8::/32 range is reserved for documentation examples, ff00::/8 represents multicast addressing, and fc00::/7 identifies unique local addressing space. Therefore, fe80::/10 is the correct answer because it is the standardized IPv6 link-local prefix.

Question 116

Which protocol securely transports management traffic over encrypted sessions?

1. Telnet
2. FTP
3. SSH
4. TFTP

Correct Answer: 3

Explanation:

Secure Shell, or SSH, provides encrypted remote-management sessions and is widely used for securely administering network devices. SSH protects interactive management traffic through encryption and provides mechanisms for authentication and session integrity. This makes it preferable to older unencrypted management protocols when secure remote access is required. Telnet transmits terminal-session information without comparable encryption, while FTP and TFTP are primarily file-transfer protocols. Therefore, SSH is the correct answer because it provides encrypted remote administrative access and is commonly used for secure Junos device management.

Question 117

Which routing protocol supports policy-based interdomain path selection?

1. RIP
2. OSPF
3. BGP
4. EIGRP

Correct Answer: 3

Explanation:

Border Gateway Protocol, or BGP, is designed for exchanging routing information between autonomous systems and supports extensive policy-based path selection. Unlike protocols primarily designed for internal network routing, BGP evaluates multiple attributes when selecting and advertising routes. Administrators can use these attributes and routing policies to control how traffic paths are selected and how routes are exchanged with different peers. RIP and OSPF are primarily interior routing protocols, while EIGRP is an interior gateway protocol associated with specific network environments. Therefore, BGP is the correct answer because interdomain routing and policy control are central characteristics of the protocol.

Question 118

Which Ethernet method negotiates duplex and speed automatically?

1. Auto-negotiation
2. Static routing
3. Route redistribution
4. Prefix filtering

Correct Answer: 1

Explanation:

Ethernet auto-negotiation allows connected interfaces to exchange information and determine compatible operational parameters such as speed and duplex settings. When both sides support compatible negotiation capabilities, they can select an appropriate common operating mode. This reduces the need for administrators to manually configure every physical Ethernet connection. Static routing, route redistribution, and prefix filtering are Layer 3 routing concepts and do not negotiate physical Ethernet characteristics. Therefore, auto-negotiation is the correct answer because it is specifically designed to establish compatible interface operating parameters between connected Ethernet devices.

Question 119

Which Junos configuration command commits candidate changes?

1. commit
2. rollback
3. load
4. deactivate

Correct Answer: 1

Explanation:

The Junos commit command activates the candidate configuration after the system validates the configuration according to the platform’s rules. Junos separates candidate configuration changes from the currently active configuration, allowing administrators to review and modify changes before committing them. The rollback command is used to return toward a previous configuration state, while load introduces configuration data and deactivate disables configured statements without necessarily removing them. Therefore, commit is the correct answer because it applies the prepared candidate configuration and makes the accepted changes operational.

Question 120

Which multicast protocol builds distribution trees between receivers?

1. PIM
2. VRRP
3. LACP
4. RSTP

Correct Answer: 1

Explanation:

Protocol Independent Multicast, or PIM, is used to establish multicast forwarding paths and distribution trees for multicast traffic. PIM works with an underlying unicast routing table to determine appropriate forwarding paths rather than maintaining an independent unicast routing protocol. Depending on the PIM mode and network design, multicast distribution can use different tree structures and mechanisms. VRRP provides gateway redundancy, LACP manages link aggregation, and RSTP provides rapid Layer 2 loop prevention. Therefore, PIM is the correct answer because it provides the multicast routing framework used to build and maintain multicast distribution paths.