Fortinet interview questions

1. Maze
2. linked list
3. string manipulate  

1st round, phone interview, 2 hrs, 4 people from the same team, network questions, OS, Linux kernel, some behavior questions.
2nd round, on site interview, 2 hrs, 4 people from the same team, same as the first round, but an on site interview.
3rd round, programming test, linked list delete node, implement a system function, maze.

Multithreading and concurrency.
Memory layout of C program.
TCP implementation, like slow start and selective ack.
Basic L2,L3 load balancing strategy, like VRRP  


what is the typical flag to pass to a common kernel function call.

How to implement STL atoi? itoa?  

C, bit manipulation,.. 

Questions from linked list, string manipulation, balanced binary tree, maze problem, stack, queue.

Here is the link to read. 

Network fundamentals:

• HSRP/VRRP/GLBP and what the differences are and how they operate on an L2/L3 basis
• STP/RSTP/MSTP and what kind of implications there can be
• FabricPath,TRILL,VXLAN (concepts at least)
• vPC,MC-LAG,MLAG,Port-Channels
• Routing (EIGRP,OSPF,BGP at the least)

Security:

• What UTM is and how it works
• How does SSL work, how does SSL interception work
• Proxies (transparent vs explicit)

Troubleshooting:

• (this is one where experience really shines, maybe your internship was in TAC, in which case you may be somewhat ready for this)
• STP problems
• FHRP common problems
• Traceroute, how does it work? What protocol does it use?
• WireShark, learn it, love it, live it
• All the checksums are wrong in my wireshark capture, whats that about?

TCP: <-- prepare to get wrecked if they quiz you on this

Honestly this one is huge. TCP is a monster I've met very few people in my life who were actually good enough to know more than just the three-way handshake. Here's a few fun ones:

• TCP windows, what are they good for, what is the implication of a smaller window, what does it mean when the window is set to zero?
• Sequence numbers, how do they work?
• What are common flags on TCP packets (hint theres more than three)
• How does PMTU work?

This is a pretty short list, but these are some common things you may end up seeing. It is a security product, but it is also a network product so a lot of non-security related things may pop up (for instance I know at least one huge Fortinet customer that uses BGP on their boxes with ECMP).