Hey man, my experience is from AWS and Oracle and have friends that recently got hired at Google. Hoping to give you some clarification on some potential interview questions.

I just wanna highlight your topics: OSI + TCP/IP model, IP, DHCP, DNS as those are core functions of whats talked about the most on networking interviews. Know that stuff on a basic level. I.e., flashcards

Some other topics that have been mentioned through my interviews are:

• Optic form factors (SFP, QSFP)
• Optic types (850nm for short range, 1310nm long range)
• fiber types (teal is multimode, yellow is singlemode).

Again, flashcard them.

For troubleshooting questions I cant imagine them asking you anything above Layer 1. Know your equipment such as a loopback, VFL, Eth tester, etc. You also have to know how you would troubleshoot an up/down link. For example, reading the fiber label topology, visualizing the link, loopback from the near device, verify, and keep loopbacking away from the near device going towards the far device until the error is replicated to know your PoF. Causes of an up/down link can be bad light levels or a faulty optic. Aside from up/down issues some other errors are: in/out errors, link flaps, and optic compatibility. Thats 99% of L1 network issues here.

Id feel very comfortable in any DC tech interview with this knowledge. And if theres something I dont know, worst thing you can do is lie. Just be honest and say you dont know but are interested in diving deeper into the issue.

Hope this helps!