Last Attempt JN0-650 Questions

The exhibit shows the output of the show poe interface command on a Juniper switch.

VTEP Power Capabilities (Statement D):The exhibit shows the Pair/Mode as 2P/AT, which refers to theIEEE 802.3at(PoE+) standard. Under this standard, a switch can supply up to30 Wof power per port to attached devices (PDs). *Dynamic Learning (Statement C):Looking at the Max power column for port ge-0/0/0, it shows 19.5W(L). The(L)indicator signifies that the power has beendynamically learned(negotiated) via LLDP or hardware classification, rather than being statically configured by an administrator. Additionally, it has identified the device asClass 4, which is a standard dynamic classification for PoE+ devices.

Why others are incorrect:Statement A (60 W) refers to the 802.3bt (PoE++) standard, which is not indicated here. Statement B is incorrect because the "(L)" confirms the configuration is not static.

In Junos OS 24.4, Captive Portal is used as a web-based authentication method for Layer 2 network access control, often in environments where 802.1X is not feasible for all users.

Fallback Mechanism (Option D):On EX Series switches, Juniper supports aflexible authentication order. By default, the switch attempts authentication in the order of802.1X, thenMAC RADIUS, and finallyCaptive Portal. If a client fails both 802.1X and MAC RADIUS, the switch can fall back to Captive Portal to redirect the user to a login page.

MAC Allowlist (Option B):Captive Portal relies on intercepting HTTP/HTTPS traffic to redirect users. However, "headless" devices like printers or cameras lack web browsers and cannot interact with the portal. To accommodate these, Junos allows administrators to configure anauthentication allowlist(or whitelist), which identifies these devices by their MAC addresses and permits them to bypass the portal entirely.

Precedence (Option A):This is incorrect because Captive Portal is generally thelastmethod in the default sequence, not the first.

Layer 2 Participation (Option C):While Captive Portal requires a Layer 3 interface (RVI/IRB) for the redirection process, it is explicitly used to controlLayer 2 accesson EX Series switches.

When a peer incorrectly floods your router with an excessive number of routes, it can exhaust system resources and crash the routing engine.

Prefix-Limit (Option B):The prefix-limit (or accepted-prefix-limit) parameter is the primary defense against such "route leaks".

You can set amaximum thresholdfor the number of prefixes allowed from a specific BGP neighbor or group.

When the limit is reached, Junos can be configured to either just log a warning ortear down the BGP sessionentirely (using the teardown keyword) to protect the router.

This prevents the "hundreds of thousand routes" from ever being fully processed or installed into the main routing table.

Damping (Option A):Damping is used to suppress unstable, "flapping" routes, but it does not limit the total volume of stable routes received.

The exhibit illustrates anEVPN-VXLANfabric using multi-homing. Server1 is dual-homed to Leaf1 and Leaf2 using anEthernet Segment Identifier (ESI)in an active-active or active-standby configuration. Server2 is single-homed to Leaf3.

In EVPN environments, specific mechanisms are used to prevent loops and duplicate traffic when dealing with Broadcast, Unknown Unicast, and Multicast (BUM) traffic:

Broadcast Propagation (Option A):When Server2 (connected to Leaf3) generates a broadcast frame, Leaf3 encapsulates this traffic into a VXLAN tunnel and forwards it to all other VTEPs (Virtual Tunnel End Points) that participate in that specific Virtual Network Instance (VNI). Therefore, both Leaf1 and Leaf2 will receive the broadcast frame from the core fabric.

Designated Forwarder (DF) Election (Option C):To prevent a multi-homed device (like Server1) from receiving duplicate copies of the same broadcast frame from multiple leaf switches, EVPN utilizes aDesignated Forwarder (DF). For a given ESI, only one leaf switch is elected as the DF.

The exhibit explicitly states thatLeaf2 is the Designated Forwarder.

According to the Junos EVPN implementation, only the DF is responsible for decapsulating BUM traffic received from the core and forwarding it to the local access segment.

While Leaf1 receives the frame (Option A), it will see that it is not the DF for that segment and will drop the frame rather than forwarding it to Server1. This ensures Server1 receives exactly one copy of the broadcast, delivered by Leaf2.

Option B is incorrectbecause in a standard ingress replication or multicast-based underlay, all VTEPs in the VNI receive the broadcast.

Option D is incorrectbecause Leaf1 is the non-designated forwarder (non-DF) for this segment and is prohibited from forwarding BUM traffic to the ESI.