Need help to prepare for your ASA interview? Look no further! Our comprehensive blog entitled “Cisco ASA interview Questions and Answers: The only guide you need will help you with the knowledge and confidence you need to succeed. Cisco has been a tech leader when it comes to network infrastructure and firewall equipment. Almost 90% of business organizations rely on Cisco for their network infrastructure devices.
The Cisco ASA is one such security appliance that provides advanced security and networking facilities for small and medium-sized businesses, service providers, enterprise organizations, and government bodies. It is one of the most popular security equipment available in the market.
This is why a lot of individuals are preparing for the role of a Cisco ASA Firewall Engineer! If you wish to land a job in the network security or network infrastructure domain, it is crucial for you to prepare how to answer Cisco ASA firewall interview questions.
In this guide, we are covering some of the most-asked interview questions and answers for the Cisco ASA Firewall. This guide will give you all the info you need to ace the job interview!
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1. What is Cisco ASA?
The Cisco ASA (Adaptive Security Appliance) is a huge security package that makes use of multiple security technologies and solutions to monitor and protect an organization’s network from cyber-attacks. It does so by using the following techniques/tools:
- Stateful packet validation
- Access Control List (ACL)
- Integrated threat mitigation tools such as antivirus, antispam, and content filtering
A Cisco ASA also has access to Virtual Private Network (VPN) remote access and high-availability features that come in handy in case of network failure or unplanned downtime.
On top of that, it also provides a safe platform to integrate additional applications such as firewalls and intrusion prevention systems. Therefore, a lot of corporate networks deploy Cisco ASA appliances and some VPNs.
Note: Cisco ASA is not a router. It is a firewall and a network security appliance.
2. What are the benefits of the Cisco ASA?
It is very important for any business organization to deploy network security and Cisco ASA is the solution for it. The following are the benefits of Cisco ASA:
- Offers network security:
Cisco ASA uses various technologies like ACL, antivirus, etc. to provide network security.
- Monitors networks and generates reports:
The major benefit of Cisco ASA is that it records various metrics in a network and generates report accordingly. This report provides information about user activity, network failures, server usage, etc.
- Provides load balancing:
Sometimes, there could be a heavy influx of traffic. This is why th Cisco ASA also has load-balancing solutions to provide security service.
- Solution to manage and monitor:
Cisco ASA also provides the facility of managing and monitoring all the devices through a single platform. No need to juggle between various interfaces.
- Easy integration with other security services:
The best feature of Cisco ASA is that it can easily work in coordination with other security services such as Cisco CloudLock, etc. This makes the detection of a threat easy.
3. What are the main features of Cisco ASA.
Cisco ASA has a variety of features that provide protection, operations control, network monitoring, and top-notch network performance.
The following are the key features of the Cisco ASA package:
- Firewall feature:
The Cisco ASA firewall provides the utmost protection from cyber-attacks along with content filtering and intrusion protection.
- Virtual Private Network (VPN):
The Cisco ASA also provides secure multi-site IPsec VPN remote access with advanced encryption and authentication.
- Real-time protection with IPS:
The Intrusion Prevention System (IPS) provides real-time protection along with a firewall. It deploys machine learning to identify threats.
- URL filtering:
This feature of the Cisco ASA allows filtering URLs to block websites and URLs. This allows network administrators to protect sensitive information from other users.
- Application control:
Cisco ASA provides information about apps running on an organization’s network. This allows network administrators to manage and control applications.
- Security intelligence:
The Cisco ASA also uses automation and analytics to provide security against cyber threats.
- Network security:
With the use of zone-based firewalls and object-based Network Address Translation (NAT), Cisco ASA provides flexible network security management.
4. What is a firewall? At which layer of the OSI model it works?
- A firewall is a network security device that acts as a protection layer between incoming and outgoing traffic.
- It allows the traffic to enter and leave the network in coordination with pre-defined rules.
- It is a device that provides security to the users as it is placed between a trusted and an untrusted network.
- Its purpose is to provide security to users, servers, and internal networks.
The firewalls work at Layer 3 (Network Layer), Layer 4 (Transport Layer), and Layer 7 (Application Layer).
5. What’s the difference between a stateful and stateless firewall?
A stateful firewall can monitor various aspects of traffic streams, their communication channels, and their characteristics.
A stateless firewall does not inspect traffic. It identifies TCP connection stages, packet state, and other updates. Their main focus is to monitor packets only.
It maintains information about connections in a connection table.
It delivers fast performance as it does not care about the traffic load.
Some examples are ASA, Checkpoint, and PIX.
An example of a stateless firewall is File Transfer Protocol (FTP).
6. Which command is used to check NAT translation?
The following commands can be used to check NAT translation:
# show xlate
# show NAT
7. Describe the different types of security events logged and monitored by the ASA.
You can consider log files as traditional physical logbooks kept by shopkeepers to enter logs for different customers. The log files record events in end-user devices or IT-based systems.
Events logs are categorized into a few default types based on the component which is at default. The following logs are made by Cisco ASA:
- Application log:
Any log that takes place is recorded by an application in this type of log. It is made by developers therefore, it is a pre-installed feature of an application.
An application error when you open an app is an example of an application log.
- Security log:
Login attempts and deletion of files are recorded in such types of logs. It depends on the administrator which logs it wants to record according to the audit policy.
- System log:
Events are logged by the operating system in such a type of log.
- DNS server log:
This type of log records the DNS server and resolution events. The access of such logs is only to the DNS server.
- Directory service log:
It keeps track of AD events. This log can only be accessed by domain controllers.
- File replication service log:
All the events that occur in the domain controller replication are recorded as an event log. This log is accessed by domain controllers only.
8. Explain security levels in Cisco ASA.
There are various security levels to check the reliability of a network attached. The security level can be configured between 0 to 100. The higher the number, the higher the trust. The Cisco ASA prefers traffic from a high-security level to a low-security level.
9. What is meant by a failover? What are the types of failover?
Failover refers to a feature exclusive to Cisco to provide redundancy. In case of a failover, two same ASA’s need to be connected to each other with a specific link. The health of units and active interfaces is monitored to check if a failover has occurred.
There are two types of failover:
- active/standby failover
- active/active failover
10. What in formation is exchanged between ASA when a failover occurs?
The information exchanged includes the following:
- State – active/standby
- Network link status
- Mac address
- Configuration replication and synchronization
- Hello messages
11. What is meant by security context?
ASA can be divided into small chunks of multiple virtual devices in the form of security context. Each of these security context acts as an independent unit with its own security policies, interfaces and administrators.
12. Mention the timeouts for TCP, UDP and ICMP sessions.
The timeouts for each of these sessions are mentioned below:
- UDP session: 2 minutes
- TCP session: 60 minutes
- ICMP session: 2 seconds
13. What is the command used for default route configuration in ASA?
ASA(config)# 0 0 <next-hope>
14. What is meant by a transparent firewall?
When a firewall acts as a layer 2 device, it is referred to as a transparent firewall. It acts as a bridge or switch and it forwards ethernet frames on the basis of destination MAC-address. There is no need for an access list to allow traffic from high security level to low security level via Layer 3.
The best part about a transparent firewall is that it can be deployed in an existing network. There is no need to reconfigure a device or re-address it before adding a transparent firewall in a network.
15. Mention all the features that are not supported in a transparent mode.
The following features are not supported:
- Dynamic routing
- VPNs like IPSec and WebVPN can’t be terminated/suspended
- ASA cannot be a DHCP relay agent
We have combined 15 most-asked ASA firewall interview questions and answers for you. Please note that this free guide should only be considered after you have covered all the fundamental concepts through the Cisco ASA course.
You can consider the Cisco ASA course as you can learn directly from Network Security Engineers with over 12 years of experience.