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MTU / MSS Path Calculator Field Guide: When Eight Bytes Quietly Break Your TCP MSS and Five Decisions Decide Whether the Overlay Survives
Tunnel math decides whether your TCP stream survives the path. Stack a 1500-byte underlay under…
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Reading 48 Bytes That Set Every Wall Clock: An NTP / SNTP Packet Field Guide
An NTP packet is not 48 random bytes — it is a 384-bit structure where…
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MTU / MSS Path Calculator Field Guide: When Eight Encapsulation Layers, the 40-Byte MSS Rule, and the Don’t-Fragment Ping Probe Decide Whether Your SD-WAN Packet Clears 1500 Bytes or Black-Holes at 1404
An overlay that drops packets is rarely a routing problem; it is a frame-size problem…
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DNS Zone File Record Builder Field Guide: When Eight Flags, One Trailing-Dot Rule, and Validation on Every Line Decide Whether Your Zone Survives a Migration
A field guide to building RFC 1035 DNS zone files: one-record-per-line syntax, SOA defaults, mail-auth TXT records, SRV/TLSA traps, and why plain text beats the registrar panel.
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Reading WebSocket Failures Fast: A Field Guide to the Five Close Codes That Drop Your Channel
Every WebSocket bug looks the same on the server: a quiet 1006 abnormal closure, a…
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DNS Query Tool Field Guide: When Seven Record Types Reveal What Your Domain Is Actually Doing
A DNS query is rarely one question. Seven record types stack behind one line of text, and the answer you actually need almost never sits in the record you thought to ask for.
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WebSocket Tester Field Guide: Four Opcodes, Seven Events, Three Bugs
A WebSocket connection is a long-lived TCP socket that both sides can write to at…
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Inside the HTTP/3 QUIC Handshake: 1-RTT, 0-RTT, and Reading a PCAP
A byte-level walkthrough of the HTTP/3 over QUIC handshake: 1-RTT fresh, 0-RTT resumption, connection migration, and how to read a packet capture without going cross-eyed.
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CIDR Calculator: The Three Numbers That Decide Whether Your Subnet Plan Survives
The slash, the network address, and the host count are the three numbers that decide whether your subnet plan survives a 1 a.m. handoff. Here is the four-line check that catches the off-by-one before it ships.
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The 12 Hex Digits That Quietly Decide Whether Your Network Trusts the Device
A MAC address is 12 hex characters. That is the entire standard. Every network interface…