Juniper Networks

JNCIS-ENT

Juniper Networks Certified Specialist Enterprise Routing and Switching

Specialist JN0-349 Content Available

Advance your Juniper expertise with enterprise routing, switching, and high-availability technologies.

Practice JNCIS-ENT Questions Study Notes Exam Topics
Exam Code
JN0-349
Duration
90 minutes
Questions
65
Passing Score
Determined by Juniper Networks
Validity
3 years
Exam Cost
$300 USD
Overview

About JNCIS-ENT

The JNCIS-ENT (JN0-349) is the specialist-level certification in the Juniper Enterprise track, building directly on the JNCIA-Junos foundation. It validates deeper knowledge of enterprise switching and routing — including VLANs, spanning tree, multi-area OSPF, BGP, high availability, and IPv6 — on Juniper EX Series switches and MX Series routers. Candidates are expected to demonstrate the ability to configure, verify, and troubleshoot enterprise network deployments using Junos OS. Topics span Layer 2 through Layer 3, from basic VLAN trunking and RSTP convergence through to BGP route reflection and Virtual Chassis stacking. The JNCIS-ENT is the stepping stone to the professional-level JNCIP-ENT and is targeted at network engineers, infrastructure architects, and operations staff who deploy and manage Juniper enterprise networks.

Prerequisites
JNCIA-Junos (mandatory) Working knowledge of VLANs, spanning tree, OSPF, and BGP concepts
Exam Domains

What you need to know

6 domains, 79 objectives. Click a domain to expand its topics.

🔌
Layer 2 Switching
EX Series architecture, VLANs, 802.1Q trunking, port security, and storm control.
20%
  • Describe the Juniper EX Series switch architecture and product family
  • Configure VLANs in Junos (VLAN ID, VLAN name, Layer 2 interface assignment)
  • Configure access interfaces and assign them to a VLAN
  • Configure trunk interfaces with 802.1Q VLAN tagging (native VLAN, allowed VLANs)
  • Describe the difference between Junos enhanced layer-2 software (ELS) and legacy configuration
  • Configure IRB (Integrated Routing and Bridging) interfaces for Layer 3 gateway on EX switches
  • Configure MAC address limiting (port security) to restrict the number of learned MACs per port
  • Configure DHCP snooping to prevent rogue DHCP servers on untrusted interfaces
  • Configure dynamic ARP inspection (DAI) to prevent ARP spoofing attacks
  • Configure storm control to limit broadcast/multicast/unknown-unicast traffic rates
  • Verify VLAN and switching operation (show vlans, show ethernet-switching table)
  • Describe the Junos Ethernet Switching Table (MAC address table) and ageing behaviour
  • Configure voice VLAN for IP telephony environments
🌲
Spanning Tree Protocols
RSTP port roles, STP convergence, MSTP instances, BPDU protection, and loop prevention.
15%
  • Describe classic STP (802.1D) operation and its limitations (slow convergence)
  • Describe RSTP (802.1w) improvements over STP (rapid convergence, port states)
  • Identify RSTP port roles (root port, designated port, alternate port, backup port)
  • Describe RSTP port states (discarding, learning, forwarding) and transitions
  • Configure RSTP on Junos EX switches and verify root bridge election
  • Configure bridge priority and port cost to influence root bridge and root port selection
  • Describe MSTP (802.1s) multiple spanning tree instances and regions
  • Configure MSTP instances and map VLANs to spanning tree instances
  • Configure BPDU protection (bpdu-block-on-edge) to shut down ports receiving BPDUs
  • Configure loop protection to prevent loops caused by unidirectional link failures
  • Configure root protection to prevent inferior switches from becoming root bridge
  • Describe PortFast/edge port behaviour and when to use it safely
  • Verify spanning tree operation (show spanning-tree bridge, show spanning-tree interface)
🗺️
OSPF (Advanced)
Multi-area OSPF, LSA types, NSSA, virtual links, summarisation, authentication, and redistribution.
25%
  • Describe multi-area OSPF design and the role of the backbone area (area 0)
  • Explain OSPF router types (internal, backbone, ABR, ASBR)
  • Describe OSPF LSA types (1 — Router, 2 — Network, 3 — Summary, 4 — ASBR Summary, 5 — External)
  • Describe stub areas and the impact on LSA flooding (blocks type 5 LSAs)
  • Describe totally stub areas (blocks type 3, 4, and 5 LSAs)
  • Describe NSSA (Not-So-Stubby Area) and Type 7 LSAs for external route redistribution
  • Configure virtual links to connect a non-backbone area to area 0 through a transit area
  • Configure inter-area route summarisation on ABRs (area-range)
  • Configure external route summarisation on ASBRs (aggregate-route in redistribution)
  • Configure OSPF MD5 authentication on interfaces and area-wide
  • Redistribute static routes and connected routes into OSPF using export policy
  • Redistribute OSPF routes into other protocols using import/export policies
  • Configure OSPF on broadcast (Ethernet) networks — DR/BDR election
  • Configure OSPF on point-to-point links and eliminate DR/BDR election
  • Verify OSPF neighbour adjacencies, LSDB, and routing table (show ospf neighbor, show ospf database)
🌍
BGP Fundamentals
eBGP vs iBGP, BGP attributes, route selection, routing policies, route reflectors, and confederations.
20%
  • Describe BGP as a path-vector routing protocol and its role in internet and enterprise routing
  • Explain the difference between eBGP (external BGP) and iBGP (internal BGP)
  • Configure a BGP peer session (eBGP and iBGP) on Junos
  • Describe BGP session states (Idle, Connect, Active, OpenSent, OpenConfirm, Established)
  • {'Explain BGP path attributes': 'AS-path, next-hop, local-preference, MED, origin, weight'}
  • {'Describe the BGP best path selection algorithm (step by step': 'highest local-pref, shortest AS-path, lowest MED...)'}
  • Configure BGP route policies for inbound and outbound filtering
  • Manipulate BGP attributes using routing policy (set local-preference, prepend AS-path)
  • Configure next-hop-self on iBGP sessions to resolve the iBGP next-hop issue
  • Describe the iBGP full-mesh requirement and scalability problem
  • Configure route reflectors and clusters to eliminate the iBGP full-mesh requirement
  • Describe BGP confederation as an alternative to route reflectors
  • Verify BGP peer state, received routes, and advertised routes (show bgp summary, show route receive-protocol bgp)
  • Configure BGP graceful restart for non-stop routing during RE switchover
⚡
High Availability
Link aggregation (LACP), Virtual Chassis, IRB, and VRRP for enterprise resilience.
10%
  • Configure Link Aggregation Groups (LAG) using LACP (802.3ad) on EX switches
  • Describe LACP active and passive modes and negotiation behaviour
  • Configure static LAG (without LACP) for non-LACP-capable peers
  • Verify LAG operational state and member link status (show lacp interfaces)
  • Describe Juniper Virtual Chassis architecture and its benefits for campus networks
  • Configure a Virtual Chassis with EX4300 or EX3400 switches (set virtual-chassis member)
  • Describe Virtual Chassis master, backup, and linecard roles
  • Configure IRB (Integrated Routing and Bridging) interfaces for inter-VLAN routing on EX
  • Configure VRRP on an IRB or routed interface for first-hop redundancy
  • Describe VRRP virtual IP, master/backup election, and preemption
  • Configure VRRP authentication and timers
  • Verify VRRP state and statistics (show vrrp, show vrrp detail)
🔢
IPv6
IPv6 addressing, EUI-64, SLAAC, DHCPv6, OSPFv3, and dual-stack deployment.
10%
  • Describe IPv6 address format and notation (128-bit, colon-hex, address compression rules)
  • Identify IPv6 address types (global unicast, link-local, unique local, multicast, anycast, loopback)
  • Explain EUI-64 interface ID generation from a 48-bit MAC address
  • Describe Stateless Address Autoconfiguration (SLAAC) using Router Advertisement (RA) messages
  • Describe DHCPv6 stateful and stateless address assignment
  • Configure IPv6 addresses on Junos interfaces (set interfaces ge-0/0/0 unit 0 family inet6)
  • Configure IPv6 static routes and verify with show route table inet6.0
  • Configure OSPFv3 for IPv6 routing on Junos
  • Describe dual-stack deployments (IPv4 and IPv6 coexistence on same interfaces)
  • Describe IPv6 transition mechanisms (6to4, 6rd, NAT64, DS-Lite) at a conceptual level
  • Verify IPv6 neighbour discovery (show ipv6 neighbors)
  • Configure IPv6 prefix on an IRB interface for dual-stack inter-VLAN routing
Resources

Study & Practice

Practice JNCIS-ENT Questions Official JNCIS-ENT Exam Page Juniper Open Learning Junos Documentation Schedule your exam via Pearson VUE