The Juniper JN0-664 exam validates your expertise in service provider routing and switching technologies. This assessment is designed for network professionals who design, deploy, and maintain carrier-grade routing and switching infrastructure using Juniper platforms. This page provides a structured study roadmap covering the core topics, question formats, and practical preparation strategies you need to pass the Service Provider Routing and Switching, Professional Exam and advance your Juniper Service Provider Routing & Switching Certification.
Use this topic map to guide your study for Juniper JN0-664 (Service Provider Routing and Switching, Professional Exam) within the Juniper Service Provider Routing & Switching Certification path.
The JN0-664 exam combines knowledge-based and scenario-driven questions to assess both foundational understanding and applied decision-making in production environments.
Questions increase in complexity as you progress, emphasizing practical troubleshooting and design reasoning over rote memorization.
Effective preparation requires a structured schedule that builds from fundamentals to integrated scenarios. Dedicate time each week to one or two topics, hands-on practice, and cumulative review to reinforce connections between routing, QoS, and VPN technologies.
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BGP, OSPF, and Layer 3 VPNs typically represent the largest portion of the exam, reflecting their critical role in service provider networks. However, all seven topics are tested, and weaknesses in any area can lower your overall score. Balance your study time by spending extra hours on BGP policy and VPN route filtering, while maintaining solid coverage of IS-IS, CoS, multicast, and Layer 2 VPNs.
In production, IGPs (OSPF and IS-IS) carry internal traffic and establish the underlay network, while BGP manages external routes and VPN customer prefixes. Layer 3 VPNs rely on both the IGP underlay and BGP overlays to distribute customer routes across PE routers. CoS policies then enforce SLA guarantees on the shared infrastructure. Understanding these dependencies is essential for troubleshooting end-to-end connectivity and performance issues.
Hands-on experience is highly valuable for building confidence and muscle memory. Prioritize labs for BGP policy configuration, Layer 3 VPN PE-CE setup, and CoS queue scheduling, as these directly map to exam scenarios. If access is limited, focus on reading configuration examples, interpreting command output, and mentally walking through configuration steps rather than skipping hands-on practice entirely.
Candidates often misunderstand BGP path selection rules, confuse IS-IS level hierarchies with OSPF areas, and overlook CoS interaction with MPLS EXP bits. Another frequent error is assuming Layer 3 and Layer 2 VPN technologies are interchangeable; they serve different use cases and have distinct configuration requirements. Careful reading of scenario details and review of protocol specifics during practice tests will help you avoid these pitfalls.
In your final week, take one full-length practice test under exam conditions and review every incorrect answer, even if you guessed correctly. Spend 20-30 minutes daily reviewing your weakest topics rather than re-reading entire chapters. On the day before the exam, do a light review of key terms and policy syntax, then rest well. During the exam itself, read each question carefully, flag difficult items for later review, and allocate time proportionally to question complexity.
In IS-IS, which two statements are correct about the designated intermediate system (DIS) on a multi-access network segment? (Choose two)
Option A (Correct):
In IS-IS, theDesignated Intermediate System (DIS)is elected based on thehighest configured priority(as defined in Junos OS).
If priorities are equal, the router with thehighest MAC addressbecomes the DIS.
A priority value of10will always override a lower priority (e.g., 1).
Option C (Correct):
On a multi-access network (e.g., Ethernet),all IS-IS routers form adjacencies with every other routeron the segment.
Unlike OSPF, IS-IS does not restrict adjacencies to only the DIS.
The DIS is responsible for creating apseudonode LSPto represent the broadcast network, but full mesh adjacencies are maintained.
Why Other Options Are Incorrect:
Option B:Incorrect. Higher priority always wins the DIS election. A priority of 1 cannot override a priority of 10.
Option D:Incorrect. IS-IS routers form adjacencies withall neighbors, not just the DIS.
Key Takeaways:
DIS Election:Prioritizes highest numerical value (e.g., 10 > 1).
Adjacency Behavior:Full mesh adjacencies are maintained, unlike OSPF.
DIS Role:Primarily for generating pseudonode LSPs and optimizing flooding, not adjacency restriction.
Exhibit
A network designer would like to create a summary route as shown in the exhibit, but the configuration is not working.
Which three configuration changes will create a summary route? (Choose three.)
To create a summary route for IS-IS, you need to configure a policy statement that matches the prefixes to be summarized and sets the next-hop to discard. You also need to configure a summary-address statement under the IS-IS protocol hierarchy that references the policy statement. In this case, the policy statement leak-v6 is trying to match the prefix 2001:db9:a:fa00::/61 exactly, but this prefix is not advertised by any router in the network. Therefore, no summary route is created. To fix this, you need to delete the longer keyword from the route-filter term and change the prefix length to /61 exact. This will match any prefix that falls within the /61 range. You also need to delete the export statement under protocols isis, because this will export all routes that match the policy statement to other IS-IS routers, which is not desired for a summary route.
By default, which statement is correct about OSPF summary LSAs?
OSPF uses different types of LSAs to describe different aspects of the network topology. Type 1 LSAs are also known as router LSAs, and they describe the links and interfaces of a router within an area. Type 3 LSAs are also known as summary LSAs, and they describe routes to networks outside an area but within the same autonomous system (AS). By default, OSPF will summarize routes from Type 1 LSAs into Type 3 LSAs when advertising them across area boundaries .
Refer to the exhibit.
Click the Exhibit button.
Referring to the exhibit, which two statements are true? (Choose two.)
In the exhibit, the output of the `show route protocol bgp` command is shown for the prefix `172.16.20.4/30`. Let's analyze the provided BGP routing table to determine which statements are correct.
1. **AS Path Analysis**:
- The AS path for the route `172.16.20.4/30` is shown as `2 I`.
- This indicates that the route was learned from AS 2 and it is an internal (iBGP) route within the same AS.
2. **Multiple Paths**:
- The route has two next-hop IP addresses: `10.0.18.2` via interface `ge-1/0/4.0` and `10.0.19.2` via interface `ge-1/0/5.0`.
- This indicates that BGP multipath is configured, which allows multiple equal-cost paths to be used for load balancing.
- BGP multipath must be explicitly configured to use multiple paths for the same prefix.
3. **Multihop vs. Multipath**:
- **Multihop Configuration**: This is typically used for establishing BGP sessions with peers that are not directly connected. It is not related to load balancing.
- **Multipath Configuration**: This is used to enable load balancing across multiple paths for the same prefix, which is the case here.
**Conclusion**:
Given the above analysis:
- **C. This route is learned from the same AS number**: Correct. The AS path `2 I` indicates the route was learned from the same AS number (AS 2).
- **D. The multipath configuration is used for load balancing**: Correct. The presence of multiple next-hops indicates that BGP multipath is configured for load balancing.
Thus, the correct answers are:
**C. This route is learned from the same AS number.**
**D. The multipath configuration is used for load balancing.**
**Reference**:
- Junos OS BGP Multipath Documentation: [Junos OS BGP Multipath](https://www.juniper.net/documentation/en_US/junos/topics/topic-map/bgp-multipath.html)
- Junos OS BGP Configuration Guide: [Junos OS BGP Configuration](https://www.juniper.net/documentation/en_US/junos/topics/concept/bgp-routing-overview.html)
Which two EVPN route types are used to advertise a multihomed Ethernet segment? (Choose two )
EVPN is a solution that provides Ethernet multipoint services over MPLS networks. EVPN uses BGP to distribute endpoint provisioning information and set up pseudowires between PE devices. EVPN uses different route types to convey different information in the control plane. The following are the main EVPN route types:
Type 1 - Ethernet Auto-Discovery Route: This route type is used for network-wide messaging and discovery of other PE devices that are part of the same EVPN instance. It also carries information about the redundancy mode and load balancing algorithm of the PE devices.
Type 2 - MAC/IP Advertisement Route: This route type is used for MAC and IP address learning and advertisement between PE devices. It also carries information about the Ethernet segment identifier (ESI) and the label for forwarding traffic to the MAC or IP address.
Type 3 - Inclusive Multicast Ethernet Tag Route: This route type is used for broadcast, unknown unicast, and multicast (BUM) traffic forwarding. It also carries information about the multicast group and the label for forwarding BUM traffic.
Type 4 - Ethernet Segment Route: This route type is used for multihoming scenarios, where a CE device is connected to more than one PE device. It also carries information about the ESI and the designated forwarder (DF) election process.
