JN0-106 Networking Fundamentals — Timed 10 Questions

Question 1

An administrator needs to ensure that traffic from the 192.168.1.0/24 subnet is allowed to reach the internet through a Juniper SRX firewall. The SRX is configured with security policies. Which policy element is required to permit this traffic?

10 minute time limit — choose an answer to begin.

Accepted Answer

Destination zone. In Juniper SRX, security policies require mandatory configuration of source zone, destination zone, source address, destination address, and application (addresses and application can be set to 'any'). For the described traffic, both the source zone (e.g., trust) and destination zone (e.g., untrust) are required to define the traffic flow. The source address is an additional match condition that can be set to the specific subnet, but it is not optional in the policy definition—it must exist (at minimum as 'any').

Answer

Source address

Answer

Application

Question 2

A network engineer is designing a redundant network with two Juniper routers running VRRP. The virtual IP address is 10.0.0.1. Both routers are configured as VRRP group 1. What is the purpose of the 'priority' parameter in VRRP configuration?

Accepted Answer

It determines the master router election.. In VRRP, the 'priority' parameter (range 1-254, default 100) is used to elect the master router. The router with the highest priority becomes the master for the virtual IP address 10.0.0.1, ensuring redundancy by taking over traffic forwarding if the current master fails.

Answer

It sets the interval for VRRP advertisements.

Answer

It determines the virtual MAC address.

Answer

It changes the virtual IP address.

Question 3

Which TWO statements about Juniper's implementation of static routes are correct? (Choose two.)

Accepted Answer

The default preference for static routes is 5.. In Juniper's Junos OS, the default preference (administrative distance) for static routes is 5. This value indicates that static routes are highly trusted, only surpassed by directly connected routes (preference 0). This is a Juniper-specific default, differing from Cisco's default of 1 for static routes.

Answer

Static routes always have a metric of 1.

Answer

Static routes are automatically redistributed into OSPF.

Answer

The default preference for static routes is 170.

Question 4

An engineer is designing a network with two routers connected via a serial link. The link should support multiple logical subinterfaces for different VLANs. Which encapsulation type must be used on the serial interface?

Accepted Answer

Frame Relay. Frame Relay is correct because it supports multiple logical subinterfaces (DLCIs) on a single serial link, allowing different VLANs to be mapped to separate virtual circuits. Unlike PPP or HDLC, Frame Relay inherently provides the ability to create point-to-point or multipoint subinterfaces for Layer 2 segmentation.

Answer

Ethernet

Answer

PPP

Answer

HDLC

Question 5

Match each Junos system log severity level to its meaning.

Accepted Answer

Emergency: System is unusable. Syslog severity levels from highest to lowest: Emergency, Alert, Critical, Error, Warning, Notice, Info, Debug. Common confusions involve swapping Warning and Notice definitions.

Answer

Warning: Normal but significant conditions

Answer

Notice: Warning conditions

Question 6

A network engineer is troubleshooting connectivity between two hosts on the same VLAN connected to different Juniper EX switches. The MAC address table on each switch shows the correct MAC addresses for both hosts, but ping fails. What is the most likely cause?

Accepted Answer

The hosts are configured with IP addresses in different subnets. Since both switches have correctly learned the MAC addresses of both hosts, Layer 2 forwarding across the trunk is working, meaning the VLAN is allowed. The ping failure therefore points to a Layer 3 issue: the hosts are configured with IP addresses in different subnets. They cannot communicate via IP without a router, even though they are on the same VLAN. The correct answer is B.

Answer

The VLAN is not allowed on the trunk between the switches

Answer

The ARP cache on the hosts is stale

Answer

Spanning Tree Protocol is blocking a port

Question 7

A Juniper EX switch has two VLANs configured, each with an IRB interface assigned an IP address. Pings between hosts in different VLANs fail. What is the most likely missing configuration?

Accepted Answer

The IRB interfaces are not in the same routing instance. On a Juniper EX switch, inter-VLAN routing works automatically when IRB interfaces have IP addresses and are in the same routing instance. No global 'IP routing' toggle or default route is required for directly connected subnets. The most likely missing configuration is that the IRB interfaces are in different routing instances, which prevents routing between them because each routing instance has a separate forwarding table.

Answer

The VLANs are not configured with the same VLAN ID

Answer

IP routing is not enabled globally: set routing-options router-id 10.0.0.1; set routing-options rib inet.0 static route 0.0.0.0/0 next-hop 203.0.113.1

Answer

The switch needs an external router configured for VLAN routing

Question 8

Two routers are connected via a point-to-point Ethernet link. They are configured with IP addresses in the same subnet, but OSPF does not form an adjacency. The link is up/up. What is a likely cause?

Accepted Answer

The OSPF hello and dead intervals are mismatched. OSPF requires that Hello and Dead intervals match between neighbors on a point-to-point link to form an adjacency. Even though the link is up/up and IP addresses are in the same subnet, mismatched timers prevent the routers from agreeing on neighbor state, so no adjacency forms.

Answer

The routers are in different OSPF areas

Answer

OSPF authentication is configured on one router but not the other

Answer

The routers have the same router ID

Question 9

Which TWO statements about ARP are correct? (Select two.)

Accepted Answer

ARP request is sent to the broadcast MAC address. An ARP request is sent as a broadcast frame to the destination MAC address FF:FF:FF:FF:FF:FF, ensuring all hosts on the local network segment receive it. This allows the host with the target IP address to respond. Option E is correct because the ARP reply is unicast directly to the requesting host's MAC address, which was learned from the source hardware address field in the ARP request.

Answer

ARP request is sent to a multicast MAC address

Answer

ARP reply is sent to the broadcast MAC address

Answer

ARP is used for both IPv4 and IPv6

Question 10

Which THREE fields are part of an Ethernet frame header? (Select three.)

Accepted Answer

Destination MAC address. The Ethernet frame header is defined by the IEEE 802.3 standard and consists of the Destination MAC address (6 bytes), Source MAC address (6 bytes), and the EtherType field (2 bytes) or Length field. The Destination MAC address is the first field in the header and identifies the intended recipient of the frame on the local network segment. Without it, switches and hosts would not know which device should process the frame.

Answer

VLAN tag (802.1Q)

Answer

Frame Check Sequence (FCS)