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The Art of Technical Troubleshooting

Author: Konrad

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Docker Image

Docker images are lightweight, read-only packages that contain everything you need to run an application: When a container is running from an image, the container is bound to that image. That means you can’t delete the image while the container is running. It is worth mentioning that an image does not contain a full OS,
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The shim (in modern Docker/containerd architecture)

The shim (in modern Docker/containerd architecture) is a small process that is started for each container. Its job is to sit between the container runtime and the container process itself. What it does enable is this: So in that sense: Important clarification: So the correct mental model is: But: Summary: The shim does not remove
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Docker – First Contact

Good option is to set docker to use this without writing sudo The Ops Perspective check the docker version Download an Image Image is similar to VM templates (for people working in operations) and to classes (for developers). check current (pulled) images Pull the ubuntu:latest image (if you don’t have it) NGINX is a server-side
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ARP Resolver

ARP – Address Resolution Protocol Communication at the link layer (Layer 2) is done using MAC addresses. If the sender’s ARP resolver does not have the destination MAC address in its ARP cache, it sends a broadcast ARP request to all hosts in the same subnet/LAN. To do this, the sender must know the IP
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MAC address

MAC – Medium Access Control MAC addresses in end-to-end communication Example path:PC → Router → ISP → Router → Server At every router: Because of this: Key takeaway MAC addresses are: IP addresses are: Mental model Worth mentioning! In this example, every host has its own MAC address, and the router also has a MAC
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Link-State (LS): How to Calculate the Shortest Path in a Graph

Imagine a graph with a few routers, and we want to find the shortest path between selected nodes. We can do this using an algorithm. To do this, we use the concept of link-state — every router has the full map. We also use the Dijkstra algorithm to find the shortest path on that map.
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IPv6 vs IPv4

IPv6 still uses 32-bit rows, like IPv4. What is different? IPv6 uses a fixed-size header, which simplifies processing. IPv6 provides a much larger address space. IPv6 removes unnecessary fields to improve efficiency. This reduces processing overhead on routers. Error detection is handled by other layers, improving performance. This keeps the IPv6 base header simple and
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NAT – Network Address Translation

If a specific host wants to reach a server on the WAN side, the traffic goes through NAT, which is applied on the router when traffic leaves the LAN. NAT (Network Address Translation) is a built-in service on the router that enables communication between the LAN and WAN. It creates a NAT translation table where
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