Troubleshooting Scenario Questions

Junos rejects configurations where both BA and MF classifiers are applied to the same interface

Why wrong: Both can be applied simultaneously.

Both classifiers are executed simultaneously in hardware without precedence

Why wrong: There is a strict processing order.

Multi-field classification is evaluated first, followed by behavior aggregate classification

Why wrong: BA is evaluated first.

Yes, all routes received by a route reflector are reflected to all peers regardless of client status.

Why wrong: Reflectors follow strict rules regarding client and non-client relationships to prevent loops.

No, route reflectors never reflect routes received from any IBGP peer.

Why wrong: Route reflectors exist specifically to reflect IBGP routes.

Yes, provided the routes contain the same Cluster ID as the receiving non-client peer.

Why wrong: Cluster IDs are for client-to-client clustering, not bypassing non-client reflection rules.

show mac-address-table interface ge-0/0/5

Why wrong: This is a Cisco IOS command, not Junos.

show ethernet-switching table port ge-0/0/5

Why wrong: While legacy EX syntax used ethernet-switching table, modern Junos uses bridge mac-table.

show l2-learning interface ge-0/0/5 macs

Why wrong: This command syntax is invalid.

Incorrect MAC mobility sequence numbers.

Why wrong: MAC mobility sequence numbers handle host moves, not DF election stability.

Exceeding the maximum MAC address table limit.

Why wrong: MAC limits restrict learning size, not DF election roles.

Using VXLAN instead of MPLS data plane encapsulation.

Why wrong: Encapsulation type does not dictate DF algorithm stability; DF is a control-plane function.

show mpls lsp extensive

Why wrong: This displays MPLS RSVP/LDP tunnel details, which are not used for pure VXLAN-based EVPN fabrics.

show spanning-tree interface

Why wrong: Spanning tree commands troubleshoot physical bridging loops, not EVPN control plane routing.

set protocols ospf area 0.0.0.2 transit-link neighbor 192.168.10.1

Why wrong: Transit-link is not a valid Junos keyword.

set protocols ospf virtual-link neighbor 192.168.10.1 area 0.0.0.1

Why wrong: This is incorrect Junos syntax.

set protocols ospf virtual-router 192.168.10.1 transit-area 0.0.0.2

Why wrong: Virtual-router is used for logical systems / routing instances, not OSPF virtual links.

An incorrect IGMPv2 timer setting on the receiver VLAN

Why wrong: IGMP timers affect host membership reports, not MSDP peering.

An invalid PIM dense-mode setting on the core interface

Why wrong: PIM dense-mode is unrelated to MSDP TCP session establishment.

set protocols lldp-med trust-qos

Why wrong: LLDP-MED advertises policies, but QoS trust state is managed under CoS configuration.

set interfaces ge-0/0/5 family ethernet-switching trust-dscp

Why wrong: trust-dscp is not a valid Junos interface statement.

set poe interface ge-0/0/5 qos-trust

Why wrong: PoE hierarchy does not control QoS trust settings.

IGMPv2 leave messages are received on an interface without active listeners.

Why wrong: Unsolicited or extra leaves do not cause RPF failures.

PIM hello messages are exchanged with an incorrect hold time.

Why wrong: Hold time mismatches affect adjacency timers, not the RPF check.

show ip ospf interface

Why wrong: Junos does not use 'show ip ospf'.

show protocols ospf status

Why wrong: This command is not valid in Junos.

show route ospf-table

Why wrong: This is not a valid operational command path.

show protocols igmp snooping vlan

Why wrong: This is an invalid operational command format in Junos.

show ethernet-switching igmp-snooping

Why wrong: While IGMP snooping relates to switching, the operational command uses 'show igmp-snooping'.

show bridge igmp-snooping querier

Why wrong: This is incorrect syntax for EX Series switches.

set routing-options multicast spt-lifetime 0

Why wrong: SPT lifetime is not a valid Junos routing-options hierarchy statement for multicast.

set protocols pim switchover-delay 0

Why wrong: There is no switchover-delay statement in Junos PIM configuration.

set protocols igmp ssm-mapping

Why wrong: SSM mapping is used for translating (*,G) joins into Source-Specific Multicast joins for receivers running IGMPv2, not for SPT switchover thresholds.

Disable LLDP-MED globally to force all phones to draw maximum class power.

Why wrong: Disabling LLDP-MED would eliminate dynamic power negotiation, likely increasing power consumption reservations rather than saving power.

Enable RSTP root guard on all voice interfaces.

Why wrong: Root guard protects STP topology, not PoE power budgets.

Convert all access ports to trunk ports.

Why wrong: Trunking does not affect PoE power budgets.

set routing-options msdp-policy <policy-name>

Why wrong: Routing options does not handle MSDP policy configuration.

set protocols pim msdp-import <policy-name>

Why wrong: MSDP import policies are configured under protocols msdp, not protocols pim.

set protocols bgp group msdp export <policy-name>

Why wrong: MSDP policies are configured under protocols msdp, not BGP groups.

HTTPS traffic is blocked by default firewall filters and is excluded from the captive portal bypass list.

Why wrong: Incorrect. It is not blocked by default, but redirection fails due to TLS security.

The captive portal server only listens on TCP port 80 and drops all incoming TCP port 443 SYN packets.

Why wrong: Incorrect. Port 443 packets are typically redirected to the portal IP, but browsers reject the invalid cert.

The captive portal profile lacks a valid SSL certificate for HTTPS traffic decryption.

Why wrong: Incorrect. Standard switches do not perform native SSL decryption for captive portals without an explicit security services module.