TCP/IP and interview?

Question

Career in IT

A job description caught my eye, which states "knowledge of the TCP / IP protocol stack is required."
I started searching, and it turned out that there are many such vacancies. Programmers, technical support, and many people really need to know this protocol stack.
It is clear that most often a specially trained recruiting robot, a female recruiter, simply copied and pasted a similar vacancy. But still, please explain what is embedded in this phrase?
What do employers ask you at interviews about the TCP/IP protocol stack?
What are you asking candidates?
ps I can talk about ISO / OSI, tracing, packets, routing, ports, protocols, and more, but the phrase itself for me is approximately equal to "knowledge of the computer is required." Is it their ignorance or my dullness?

Answer 1

When I was interviewing, I wanted to see something like the following:
- Know about the levels, at least clearly answer what is on the second and what is on the third.
- Understand the structure and operation of TCP / IP 4. Write a network / mask correctly, know what a gate is, explain the difference between tcp / udp, know what ping and trace are, how and with what protocols they work, give examples of network services.
If the candidate has this knowledge, you can immediately see how clearly the person answers general questions, if they don’t, you can kick him out.

Answer 2

Selections from our primitive mini-questionnaire:
1. What are the advantages and disadvantages of singlemode and multimode optical cables?
2. Which Ethernet cable (straight or cross) will you connect:
- 2 hosts
- host and switch
- 2 switches
- switch and router
- 2 routers
- host and router
...
4. The following static routes are specified on the host (in the format of Windows commands) :
route add 10.128.0.0 mask 255.240.0.0 10.0.0.1
route add 10.0.0.0 mask 255.0.0.0 10.0.0.2
route add 10.128.0.0 mask 255.255.240.0 10.0.0.3
Through which gateway will the route go to host 10.128.1.1?
5. How will a 5000 byte UDP datagram be split with MTU=1500?
…
7. List the order of service packets at the time of establishing a TCP connection.
8. Draw (list) the packet headers indicating the IP addresses transmitted over the tunnel:
— GRE;
- IPSEC (in transport mode);
- IPSEC (in tunnel mode).
…
10. What does each field of records in the company.ru domain zone mean:
10 MX omega.company.ru
5 MX lambda.company.ru

None of the applicants answered the 2nd question correctly…

Answer 3

IMHO this is equivalent to the phrase "requires experience with the network" and can mean a lot.
PS. mapping of TCP/IP protocols to OSI levels is not unambiguous :) and in general, who except the architect of network interfaces needs this?

Answer 4

Hmm... and I can briefly tell the contents of the TCP packet, tell about all the states... I wonder if they will ever ask =)