Quiz: Packet Path

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2 questions

L1 (1 questions)

1. A curl request times out. How do you systematically narrow down where the problem is?

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1. DNS: does dig resolve?
2. Connectivity: does ping/nc reach the port?
3. Routing: does traceroute show where packets stop?
4. Firewall: check iptables on both ends.
5. Service: is the process listening (ss -tlnp)?
6. TLS: does openssl s_client connect? Narrow from L3 up to L7.

L2 (1 questions)

1. How do you trace the path of a packet through a Linux system?

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1. tcpdump on the interface to confirm arrival.
2. conntrack -L to check NAT/state table.
3. iptables -L -v counters to see which chain processes it.
4. ip route get to check routing decision.
5. ss -tlnp to verify the listening process. Trace: NIC -> iptables PREROUTING -> routing -> FORWARD or INPUT -> app.