Introduction

Are you preparing for a CCIE interview? If so, you must already be aware of the fact that clearing this interview is not easy. It requires a lot of hard work, dedication, and thorough knowledge of the Cisco networking technologies. But with the right preparation and guidance, you can turn this challenge into an opportunity to shine. Hence, fear not! We have got your back.

In this blog, we have hand-picked the top 20 CCIE interview questions and answers in order to crack the interview with ease. These questions cover network fundamentals as well as advanced routing and switching concepts. With the right preparation, including comprehensive CCIE Enterprise Infrastructure training, you can confidently showcase your expertise and impress your interviewers.

Let’s not wait any further and discuss the most asked CCIE interview questions and answers that every CCIE must know.

Top Basic CCIE interview questions and answers

The CCIE Interview questions and answers we are going to discuss will help you in getting a clear idea of what to expect in the interview. Also, after going through these questions, you will become more confident and ready. Let’s Begin!

Here are the top 10 most asked basic CCIE Interview questions –

Q1 – What are the five ICMPv6 messages used by the Neighbor Discovery Protocol?

The five ICMPv6 messages that we are going to discuss are used by NDP to manage node-to-node and node-to-router communication on a link. It allows features such as autoconfiguration, duplicate address detection, and next-hop determination. These are:

• Router Solicitation: Sent by a node to request routers to advertise their presence on the link.
• Router Advertisement: Sent by routers in response to RS (Router Solicitation) messages in order to advertise their presence as well as configuration parameters.
• Neighbor Solicitation: Sent by a node in order to request the link-layer address of a neighbor. It is also to verify the reachability of a neighbor.
• Neighbor Advertisement: Sent by a node in response to NS (Neighbor Solicitation) messages in order to provide its link-layer address or can also be used to indicate that it is reachable.
• Redirect: Sent by a router to inform a node of a better first hop for a destination.

Q2 – What is the purpose of a DMZ (Demilitarized Zone) in network security?

The main purpose of a DMZ is to offer an additional layer of security in order to protect the internal network from unwanted or untrusted traffic. The protection is done by segregating public-facing services and servers from the rest of the internal network.

Some of the most common devices and services placed in a DMZ include:

• Web servers
• Email servers
• VPN servers
• Firewalls
• Proxy servers
• Intrusion detection and prevention systems (IDPS)

Q3 – Explain the principles of SDN and the role of protocols like OpenFlow in enabling programmable network control.

SDN or Software Defined Networking is a network architecture that separates the control plane (decision-making) from the data plane (Forwarding) in a network.  This allows for centralized, programmatic control of network behavior.

Now, the OpenFlow protocol is a key enabler of SDN i.e., provides a standardized interface between the control plane and data plane. OpenFlow further allows the controller to program the forwarding behavior of network devices (switches and routers) by defining flow rules. This programmable network control allows network administrators to adapt to any network changes and requirements quickly. Also, assists them in optimizing performance and implementing advanced network services and applications.

Q4 – What is the role of MLD (Multicast Listener Discovery) in IPv6?

In IPv6, MLD or Multicast Listener Discovery plays an important role in managing multicast group membership. It allows IPv6 nodes to inform their local routers about their interest in receiving multicast traffic from specific multicast groups. This information is then further used by the routers to forward multicast data. In the forwarding process, multicast data is only sent to the network segments that have interested listeners. With this, one can optimize the use of network resources.

Q5 – Discuss the various Spanning Tree Protocol (STP) modes and their impact on network convergence and redundancy.

STP modes are mainly used to determine how a network converges and maintains redundancy. Common modes include:

• STP (802.1D): This mode is the original implementation of the STP standard in which a single instance of a spanning tree is allowed in a LAN.
• Rapid STP (RSTP, IEEE 802.1w): It is an upgraded version of standard Spanning Tree Protocol. Faster convergence when compared to STP. Still has limitations and one of many is the same as STP 802.1D i.e., a single instance of a spanning tree is allowed in a LAN.
• Multiple Spanning Tree (IEEE 802.1s): It supports multiple VLANs as well as allows to creation of separate spanning tree instances. This in return improves scalability and convergence.
• Rapid Per-VLAN Spanning Tree (RPVST+): It combines both RSTP and MST which in return offers fast convergence and scalability. It is one of the Cisco-spanning-tree modes in which Cisco-proprietary enhancements were made to RSTP, IEEE 802.1w.
• Per-VLAN Spanning Tree (PVRST): It is also one of the Cisco spanning-tree modes in which Cisco-proprietary enhancements were made to STP, IEEE 802.1w. It is similar to RPVST+ but with improved convergence.

Q6 – What is the purpose of route invalidation timers?

When a router learns about a route from a neighboring router, it stores the route in its routing table along with a timer. This timer is called the route invalidation timer or route timeout timer.

Route invalidation timers are a crucial component of routing protocols, and their purpose is to ensure that routing information remains accurate and up-to-date.

The main purpose of the route invalidation timer is to:

• Detect route failures
• Remove stale routes
• Trigger route recalculations

Q7 – What is the role of Cisco Firepower in network security?

Cisco Firework is a network security solution that offers many security measures. Some of these are threat defense, intrusion prevention, and advanced malware protection. It integrates with many Cisco security products in order to detect as well as block threats in real-time. This provides visibility, control, and protection across the network.

Q8 – How would you troubleshoot a routing loop in an OSPF network, and what tools would you use to identify the issue?

In order to troubleshoot a routing loop in an OSPF network, you can use the below steps.

• Identify symptoms: Look for packets being forwarded in a loop, high CPU usage, and increased network latency.
• Verify OSPF configuration: With the help of ‘show ip ospf interface’ you can check OSPF process ID, area IDs, and interface configurations for inconsistencies.
• Analyze OSPF database: Use ‘show ip ospf database’ to examine the LSDB for duplicate or inconsistent entries.
• Check routing tables: Use ‘show ip route ospf’ command to display the OSPF routes in the routing table. Also, you can make use of ‘show ip ospf border-routers’ command in order to get the information regarding OSPF border routers. With these commands, you can easily identify routes with multiple paths or inconsistent metrics.
• Debug OSPF packets: Enable ‘debug ip ospf ’ command in which you can use various debugging options which include events, packets, hello, and errors. For example, if you use ‘debug ip ospf packet’, it will capture and analyze OSPF packet exchanges.

Tools Used:

• Cisco IOS commands: ‘show ip ospf database’, ‘show ip ospf interface’, ‘show ip route ospf’, ‘debug ip ospf ’
• Network Protocol Analyzers: Wireshark, Tcpdump, etc.

Q9 – What is the difference between a point-to-point and a point-to-multipoint connection?

Here are some differences between the two –

Q10 – What is the purpose of the IP SLA feature on Cisco routers, and how can it be used to monitor network performance?

IP SLA is a Cisco router feature with which one can monitor as well as measure network performance, ensuring that service level agreements are met. The purpose of the IP SLA feature on Cisco routers are:

• Monitor network performance
• Verify network connectivity
• Troubleshoot network issues

IP SLA can be used to monitor network performance metrics such as Latency, Jitter, Packet Loss, Throughput, Response time, etc.

IP SLA can be used to monitor network performance by means of simulating real-world traffic. Further, it assists in identifying bottlenecks and offers data for troubleshooting and optimization.

These are the top basic CCIE Interview Questions and answers. Moving on let’s see some advanced ones too.

Advanced CCIE Interview Questions and Answers

Here are the most asked advanced CCIE Interview Questions with answers.

Q11 – What is a recursive table lookup?

A recursive table lookup, also known as a recursive route lookup, is a feature on Cisco devices that allows the router to perform a second lookup in the routing table to resolve a recursive routing decision.

Let’s understand in detail for better understanding.

• Firstly, the router receives a packet and then performs a normal routing table lookup in order to determine the next hop. 
• If the next hop is a recursive route i.e., a route that points to another route instead of a directly connected interface. The router then performs a second lookup in the routing table to resolve the recursive route.
• The second lookup uses the result of the first lookup as the new destination IP address.
• The router continues to perform recursive lookups until it finds a route that points to a directly connected interface or final destination.

Q12 – How does address summarization help stabilize a network in BGP?

Address summarization in BGP assists in stabilizing a network by reducing the number of routes that need to be exchanged and stored. This can only be achieved by combining multiple specific routes into a single route.

Example: Instead of advertising individual routes for 192.168.1.0/24, 192.168.2.0/24, and 192.168.3.0/24, a network can summarize these into a single route of 192.168.0.0/16. This helps reduce the size of the routing table which further assists in decreasing the processing and memory requirements for routers. With this, network stability will be improved and also result in faster convergence times when network changes occur.

Q13 – Explain the concept of VXLAN and its advantages over traditional VLAN-based network architectures.

VXLAN or Virtual eXtensible Local Area Network is a layer 2 overlay technology. It allows for the extension of Layer 2 networks over Layer 3 networks. It is used to encapsulate Ethernet frames within UDP packets which enables the creation of VLANs. These VLANs can span across multiple physical networks.

VXLAN offers many advantages over traditional VLAN-based network architecture. Some of these are:

• Better scalability & flexibility
• Multi-tenancy
• Simplified network management
• Improved network resiliency
• Better support for virtualization and cloud computing

Q14 – What is the purpose of DFS in Wi-Fi?

DFS or Dynamic Frequency Selection is a mechanism in Wi-Fi that allows APs to dynamically switch to a different channel in the 5 GHz frequency band. This is simply to avoid interference with radar systems used by weather monitoring, the military, and many other applications.

The main purposes of DFS in Wi-Fi are:

• Avoid interference with radar systems
• Minimize interference to Wi-Fi networks
• Comply with regulatory requirements

Q15 – Explain the concept of Cisco Meraki in cloud-managed networking.

Cisco Meraki is a cloud-managed networking solution that offers a centralized cloud-based platform to manage as well as monitor network infrastructure via a web-based Meraki dashboard from anywhere. Meraki became part of Cisco’s CNG (Cloud Networking Group) in 2012.

Some of the features of Cisco Meraki are:

• Cloud-based Management: Meraki’s cloud-based management platform is also known as the Meraki dashboard. It allows network administrators to manage as well as monitor their network infrastructure via a simple interface.
• Network Devices: Cisco Meraki offers a range of network devices such as wireless access points, switches, security appliances, and many others. These devices are designed to work seamlessly with a cloud-based management platform.
• Cloud-based Architecture: It is built around cloud-based infrastructure which offers better scalability, reliability, and flexibility.

Q16 – What is the main difference between public, private, and hybrid clouds?

The basic difference between the public, private, and hybrid clouds is:

Q17 – What is the role of zero-trust security in modern networks?

In modern networks, zero-trust security plays a crucial role by assuming that all users and devices, whether inside or outside the network, are potential threats. It verifies the identity and permissions of every access request, using multi-factor authentication, encryption, and micro-segmentation to limit lateral movement and protect sensitive data.

Q18 – What is the difference between a Stateful failover and a Stateless failover?

The basic difference between a stateful failover and a stateless failover is:

Q19 – How does FCoE (Fibre Channel over Ethernet) work in data centers?

FCoE or Fibre Channel over Ethernet is a storage networking protocol that assists in allowing the Fibre Channel traffic to run over Ethernet networks in data centers. With FCoE, it is possible to converge the storage and network traffic onto a single high-speed Ethernet infrastructure.

FCoE works by encapsulating FC frames in Ethernet packets. This allows them to be transmitted over 10GbE or faster networks. FCoE switches and adapters convert FC traffic to Ethernet and vice versa. This enables seamless communication between FC storage and Ethernet-based servers and makes it an attractive solution for data center infrastructure.

Q20 – What is MQC?

Cisco Modular Quality of Service (MQC) is a policy-based QoS framework. It allows network administrators to define, implement, and manage QoS policies across a network. It provides a modular, flexible, and scalable approach to QoS configuration. With this one can enable granular control over traffic classification, marking, policing, and shaping. Most importantly, it makes use of all those platforms that are supported by Cisco IOS software.

These are the top advanced CCIE Interview Questions and Answers.

Conclusion

You now have the top CCIE interview questions and answers to get you started. Remember, the 20 questions we have shared with you are just a starting point. It doesn’t mean that only these questions will be asked in your interview. Instead, use these questions and answers as a guide only. The only way you can clear a CCIE interview is by understanding the concepts, practicing regularly, and staying confident.

So, take this as a starting point and practice more such questions to clear the CCIE interview. Good luck with your interview.

If you have any more CCIE interview questions, feel free to ask in the comment section below.