yuval.guide — Guides and hands-on courses on DevOps, cloud, Linux, Python, Kubernetes, networking and AI.

TLS is what turns the password of Basic HTTP Authentication from readable text into ciphertext. Before any HTTP is sent, the client and the server agree on a secret that nobody on the path can compute. The server proves that it holds the private key of a certificate issued for the name the client typed. Every record of …

When a link fails, the routers at its two ends describe the network afresh and flood the news to everyone in the area; every router then reruns SPF on the new database. The demo cuts the R1B–R1D link in area 1 of the network from the earlier demos, while a host on R1A's LAN sends a steady stream of packets to ABR-1B, …

Inside an area every router holds the whole map, but no router LSA ever leaves its area. Routes between areas are carried by the ABRs as summary LSAs: a prefix and a cost, with nothing of the links behind them. This demo follows one such route from area 2 to area 1 across the network from the Hello, Database Exchange …

Every router in an OSPF area holds the same database, and runs Shortest Path First (SPF) on it to find the cheapest path to everywhere in the area. This demo takes area 1 of the network from the Hello and Database Exchange demos, strips it down to a graph, and runs Dijkstra's algorithm on it one decision at a time. …

Two OSPF neighbors that have agreed to become adjacent still hold different link-state databases. The database exchange makes them identical: each describes what it holds, asks for what it lacks, and receives it. This demo runs that exchange on the same network as the Hello protocol demo, one adjacency at a time. The …

The Hello protocol is how OSPF routers find each other, agree that they can talk, and elect a Designated Router on a shared segment. This demo runs it on a fixed network of eleven routers; there is nothing to configure, only a scenario to watch. The network in the demo Area 0 is one switched segment joining the four …

Click a bit to flip it, count with the ▲ ▼ arrows, or type the byte's value in decimal or hex — the fields that changed stay marked until the next change. Byte (8 bits) ▲ ▼ Decimal (0–255) ▲ ▼ Hex (00–FF) ▲ ▼ ×16 ×1 ▲ ▼ Character Description The byte and its eight bits A bit is a single 0 or 1. A byte is eight bits, …

Bytes and character sets Bits, Bytes and ASCII

On this page: What the retrieval half of langchain-core is Index Pinned version: langchain-core==1.6.3 (released 2026-09-11) — the same package as the langchain-core reference; that page covers the chat and tool types, this one covers the retrieval types. Two extras are needed for the examples: numpy (resolved to …

On this page: What langchain-text-splitters is Index Pinned version: langchain-text-splitters==1.1.2 (released 2026-04-16; it is the version pip resolves beside langchain-core==1.6.3, and its only requirement is langchain-core<2.0.0,>=1.2.31). Everything below was derived by inspecting this exact installed package, …