Addressing, DNS, DHCP and NAT — and a method for finding which of them is broken.
It is being written. The outline below is what it will cover, and it is unlikely to change much. There is no enrolment and no date — when it is ready it will be on this page. Several of the lessons are built around tools on this site that already work, so you can practise the measurements today.
If you need this capability now rather than later, Managed network operations is the service that covers it, or talk to us.
First- and second-line support staff who can follow a runbook and would like to know why it works.
Foundation. No prior experience assumed. Written for people whose job is not IT.
No prerequisites. Nothing is assumed beyond using a computer at work.
3 modules, 10 lessons, 1 h 58 m of material. The times are the sum of the lessons rather than a round figure.
The arithmetic, and what it tells you about where a packet can and cannot go.
What the mask is for, and reading a prefix length without converting to binary.
Splitting a block, and why allocating largest-first avoids stranding the space.
The reserved ranges, and why an address beginning 100.64 cannot accept an inbound connection.
What is genuinely different, and what is the same with longer numbers.
Most things reported as "the network is down" are name resolution.
Stub resolver, recursive resolver, authoritative nameserver, and the caches between them.
A, AAAA, CNAME, MX, TXT, SRV, PTR — and the CNAME rule people break.
Caching, negative caching, and planning a cutover around both.
A method, so the answer does not depend on which layer you happened to guess.
Link, address, gateway, name, route, application — in that order, every time.
Why a hop that does not reply is almost never the fault.
The symptom that looks like nothing else, and how to confirm it.
Format. Written lessons with exercises you can work through using this site’s subnet calculator and DNS tools. Delivery mechanism is not built yet.
These tools run the same checks the course teaches, and they work today. No account, and the ones marked as running in your browser send nothing anywhere.
Why calls break up on a connection that tests clean, and how to prove where the fault is.
Course outline ⟶Chains, names, renewal and the expiry that takes a service down on a Sunday.
Course outline ⟶The attacks that pass SPF, DKIM and DMARC, and the habits that catch them anyway.
Course outline ⟶This course exists because the work behind it is work we do. If you need the result rather than the skill, managed network operations is the service that covers it.