To succeed in the technical rounds, you need to anticipate the specific domains your interviewers will focus on. The technical evaluations at DXC Technology heavily favor applied knowledge over theoretical concepts.
Firewall Architecture and Management (Palo Alto Focus)
Firewalls are the core of this role. You will be expected to have a strong command of next-generation firewall (NGFW) concepts, with a particular emphasis on Palo Alto Networks. Interviewers want to see that you understand how to manage policies, configure security profiles, and utilize advanced features to protect enterprise perimeters.
Be ready to go over:
- Packet Flow – A deep understanding of how a packet traverses a firewall, including NAT, policy evaluation, and inspection phases.
- App-ID and User-ID – How to implement and troubleshoot application-layer and user-based routing and security policies.
- Security Profiles – Configuring and tuning Antivirus, Anti-Spyware, Vulnerability Protection, and URL Filtering.
- Advanced concepts (less common) – Panorama management, template stacking, and zero-trust architecture implementations.
Example questions or scenarios:
- "Walk me through the exact packet flow when a user attempts to access an external website through a Palo Alto firewall."
- "How would you migrate a legacy port-based rule to an App-ID based rule without causing an outage?"
IPSEC VPNs and Cryptography
Secure communication between sites is a critical responsibility. You will be tested extensively on your knowledge of Virtual Private Networks, specifically IPSEC VPNs. You must understand the underlying cryptography, the negotiation phases, and how to build robust, secure tunnels.
Be ready to go over:
- IKE Phases – The differences between IKE Phase 1 and Phase 2, including Main Mode vs. Aggressive Mode.
- Cryptographic Protocols – Understanding ESP, AH, encryption algorithms (AES), and hashing algorithms (SHA).
- NAT-Traversal (NAT-T) – How and why NAT-T is used when establishing VPNs across intermediate firewalls or routers.
Example questions or scenarios:
- "Explain the steps of IKE Phase 1 negotiation. What parameters must match for it to succeed?"
- "A site-to-site IPSEC VPN is down. Phase 1 is up, but Phase 2 is failing. What are the most likely causes and how do you troubleshoot them?"
High Availability (HA) and Redundancy
Because DXC Technology supports mission-critical environments, downtime is unacceptable. You will be evaluated on your ability to configure and troubleshoot High Availability (HA) pairs to ensure seamless failover during hardware or software failures.
Be ready to go over:
- Active/Passive vs. Active/Active – The use cases, benefits, and drawbacks of different HA deployments.
- HA Links and Synchronization – The roles of HA1 (Control Link) and HA2 (Data Link), and how state synchronization works.
- Split Brain Scenarios – How to identify, prevent, and recover from a split-brain situation in a firewall cluster.
Example questions or scenarios:
- "What happens to existing TCP sessions during an Active/Passive failover event on a Palo Alto firewall?"
- "You notice that your secondary firewall is marked as 'Suspended'. How do you investigate and resolve this HA state issue?"
Basic Network Troubleshooting
A Security Engineer must be a strong network engineer first. You will face scenarios that require you to diagnose routing, switching, and connectivity issues that intersect with security policies.
Be ready to go over:
- Routing Protocols – Basic understanding of OSPF, BGP, and static routing as they apply to firewall traffic forwarding.
- TCP/IP Fundamentals – The TCP 3-way handshake, subnetting, and analyzing packet captures (PCAPs).
- Diagnostic Tools – Effectively using ping, traceroute, telnet, and firewall-specific diagnostic commands.
Example questions or scenarios:
- "A user complains they cannot reach a specific server on a different subnet. Walk me through your troubleshooting steps from the client machine to the firewall."