Lesson 01 — What Networking Means in DevOps, and IP Addresses

Track: DevOps Networking — 1 Month Deep Dive Part: 1 — Networking Foundations Status: Understood and closed Concepts covered: 2 — networking in DevOps, IP address

Table of contents

1. Concept 1 — What networking means in DevOps
2. Concept 2 — IP address
3. Questions raised in this lesson
4. Easy to get wrong
5. Old way vs improved understanding
6. Terms locked in
7. Deliberately not covered yet
8. Sources

Concept 1 — What networking means in DevOps

The starting point

Take one computer running one program. Inside that program, when part A needs something from part B, it just calls it. Instantly. Nothing to configure. Nothing to break.

Now take that same program and split it into pieces, each running on a different machine:

web piece    →    backend piece    →    database piece
(machine 1)       (machine 2)           (machine 3)

Nothing about the code changed. But now, when the web piece wants something from the backend piece, it can no longer just “call” it. It has to send that request out of machine 1, across a wire, and into machine 2.

That sending is networking.

Definition

Networking is how one machine reaches another machine and gets an answer back.

Why this becomes a DevOps concern

The arrow between machine 1 and machine 2 does not exist by default. Somebody has to make it exist. Somebody has to decide:

• which machine is allowed to talk to which,
• at what address,
• through which door.

When that arrow is missing or pointed at the wrong place, the application looks perfectly healthy — the process is running, the logs are clean — and users still get an error.

What problem it solves

Modern applications are spread across many machines. Most production failures in that world are not broken code. They are broken arrows. Networking knowledge is what turns “it’s broken” into “the traffic dies between point X and point Y.”

Where it sits

Everything in this track lives on one line:

user → DNS → load balancer → proxy/ingress → service → container → app

Every future topic is one hop on this line. Learn the hops one at a time, and eventually you can trace a request end to end.

Concept 2 — IP address

The problem it solves

Machine 1 needs to send a request to machine 2. But a network has many machines on it — ten, a thousand, a million. So the network needs a way to tell them apart.

The solution

Give every machine a number.

That number is the IP address. It looks like this:

10.0.1.57

Four numbers separated by dots. Every machine on the network has one, and no two machines on the same network share the same one.

How it is used

When machine 1 sends its request, it writes the destination number on it before sending:

machine 1  ──[ deliver this to 10.0.1.57 ]──►  machine 2

The network reads that number and carries the request to the machine holding it.

Definition

An IP address identifies one machine on a network.

Example from everyday experience

Connect a laptop to home WiFi and it gets one of these numbers automatically. The phone gets a different one. The TV gets another. Same network, three machines, three different numbers — so the router can tell them apart when data comes in.

What breaks without it

Machine 1 has a request ready and no way to say where it should go. Nothing can be delivered.

Questions raised in this lesson

Who decides this number?

Two different answers, depending on which network is meant.

Inside a private network (home WiFi, an office): the router hands out the numbers automatically. It keeps a small list and assigns one to each device that connects. Nobody outside is involved.

On the internet: the numbers cannot be handed out casually, because if two machines anywhere in the world had the same number, delivery would break. So there is one global organisation that holds the whole pool of numbers — IANA (Internet Assigned Numbers Authority). IANA does not give numbers to individuals. It gives large blocks to five regional organisations, called Regional Internet Registries (RIRs), and those give smaller blocks to the companies that provide internet connections, who then give one to each customer connection.

The chain looks like this:

IANA (global pool)
   ↓
5 Regional Internet Registries
   ↓
internet service providers
   ↓
you

The five RIRs cover Asia-Pacific (APNIC), Europe and the Middle East (RIPE NCC), North America (ARIN), Latin America and the Caribbean (LACNIC), and Africa (AFRINIC).

Who sets the ranges?

The ranges come from published technical standards, not from a company decision.

The reserved private ranges — the ones a home router or an internal company network uses — are defined in a standards document called RFC 1918, published in 1996. It reserves exactly three blocks:

10.0.0.0     – 10.255.255.255
172.16.0.0   – 172.31.255.255
192.168.0.0  – 192.168.255.255

Two important details from the standard itself:

• An organisation can use these addresses without asking IANA or any registry for permission. They are free for anyone to use internally.
• Addresses in these ranges are only unique inside one organisation. They are not routable on the public internet, and internet providers’ routers are expected to filter them out.

How many IP addresses exist in the world?

This is calculable. Four slots, each holding a value from 0 to 255. That is 256 possibilities per slot:

256 × 256 × 256 × 256 = 4,294,967,296

Roughly 4.3 billion addresses. That is the entire supply of this address format.

In the standards this is described as a 32-bit address — 32 binary digits, producing 2³² combinations, the same number.

Can it finish? What happens if it finishes?

It already finished.

4.3 billion sounded infinite when the format was designed in the early 1980s, when only universities, research organisations and government agencies were connected. Then came home computers, then phones, then every laptop, tablet, camera, TV and machine in every data centre on Earth — most people now consume several addresses at once.

The global pool was emptied on 3 February 2011. IANA handed its final five blocks to the five regional registries in one ceremony, triggered by an agreed global policy, and after that there were no fresh addresses left at the top level.

The regional pools then drained over the following years, each at its own pace:

What happened when it ran out: nothing dramatic. The internet did not stop, for one reason — most machines do not need a globally unique number.

Go back to the home WiFi example. Laptop, phone and TV each had their own number, but those numbers are only meaningful inside the house. The whole home shares one internet-facing number, and the router translates in both directions. So one global address can cover a household, an office, or thousands of machines.

That trick bought the internet an extra fifteen-plus years. It is a workaround, not a fix — and it is the reason the real solution exists.

What exists today instead of fresh addresses: a resale market. Organisations buy unused blocks from each other through the registries’ transfer process. Roughly 29.7 million addresses changed hands in the first half of 2026 alone, at a published-price average of about $20 per address. Prices peaked far higher around 2021–22 and have fallen since.

What is the difference between IPv4 and IPv6?

Everything above describes IPv4 — version 4, the four-numbers-with-dots format, 32 bits, ~4.3 billion addresses.

IPv6 is version 6, designed specifically to end the shortage. Instead of 32 bits it uses 128 bits, written like this:

2001:0db8:85a3:0000:0000:8a2e:0370:7334

Eight groups separated by colons, using hexadecimal (digits 0–9 plus letters a–f). The supply it produces is around 340 undecillion — a number with 39 digits. It will not run out.

The detail that matters most: the two are not compatible. An IPv6-only machine cannot talk to an IPv4-only machine directly. That means the world cannot simply switch over — every network has to support both during the transition. This is exactly why IPv6 has been “coming” since its first specification in December 1998 and is only now reaching majority use.

Current adoption: IPv6 crossed 50% of Google’s measured traffic for the first time on 28 March 2026 (50.10%), up from 46.33% a year earlier. So in practice: expect IPv4 daily, but IPv6 is no longer a minority protocol.

Who decided the IPv6 pattern, and what kind of people are involved?

IPv6 was designed by the IETF — the Internet Engineering Task Force.

It is not a company. It is not owned by anyone. There is no CEO, no shareholders, and no government controls it.

Who participates: it is an open group of engineers, and anyone can join. There is no membership fee and no application process. The IETF’s own documents state plainly that it is not a membership organisation — there are no “members,” only “participants,” and this is precisely why they cannot hold votes: it would be impossible to determine who was entitled to vote. Most participants work at companies that depend on the internet functioning (network equipment vendors, internet providers, large software companies, universities), but they participate as individual engineers.

How a decision is actually made:

Someone writes a proposal and publishes it for anyone to read and attack. Others tear it apart, argue, and propose alternatives. This happens on public mailing lists and at meetings held three times a year. Every discussion is public and archived — the arguments people had about IPv6 in the 1990s are still readable today.

Two things make this group unusual:

1. There is no vote. Decisions are made by rough consensus — not everyone agreeing, but no one holding an objection serious enough to stand. Their founding principle, stated in a 1992 talk and quoted in their own standards documents, is: reject kings, presidents and voting; believe in rough consensus and running code. Critically, the documented rule is that an objection has to be genuinely considered and technically answered — a group cannot simply dismiss it because more people disagree. A single engineer with a valid technical objection can hold up a proposal backed by a large company.

2. Running code beats theory. A design is not accepted because it looks good on paper. Practical implementation experience outweighs theoretical elegance.

If a proposal survives all of that, it is published as an RFC — a numbered public document that becomes the official specification. These are free, public and permanent. Anyone can read them.

Why IPv6 looks the way it does:

The specific decisions came out of arguments over trade-offs. The address length is the clearest example. Once the group accepted IPv4 was running out, the obvious question was how much bigger to go. Some argued for a modest increase — easier to transition, less data attached to every request. Others argued that if you are going to force the entire world through a painful upgrade, you do it once and never again.

The second group won. The address was made deliberately, almost absurdly larger than needed, so the question would never return. The colon-separated hexadecimal format exists because writing an address that long in the old four-number decimal style would be unreadable.

The competing proposals and the reasons they lost are all in the public archives.

Easy to get wrong

Traps in this topic worth remembering.

The private range in the middle is not all of 172. It is 172.16 through 172.31 only. 172.32.x.x is a public address. Filtering or firewalling 172.x.x.x as a whole is a real and common mistake.

“Exhausted” does not mean “unavailable.” IPv4 addresses still get allocated every day — through resale and recovery, not from a fresh pool. The distinction matters when reading announcements: “IANA’s pool is empty” and “you cannot get an IPv4 address” are different statements.

Private addresses are not a security feature by themselves. They are unreachable from the internet because no router will carry them, not because something is actively blocking traffic. That distinction matters later when access control comes up.

A machine can hold more than one address. Nothing in the definition says one machine has exactly one IP. This becomes important with containers and cloud instances.

Old way vs improved understanding

Terms locked in

Terms now known and usable freely going forward:

• network — the set of paths that let machines reach each other
• IP address — the number identifying one machine on a network
• IPv4 — the 32-bit, four-numbers-with-dots format
• IPv6 — the 128-bit, colon-separated hexadecimal format
• private address range — the RFC 1918 blocks, usable internally by anyone, not routable on the internet
• IANA — the global holder of the address pool
• RIR — one of the five regional registries that distribute addresses
• IETF — the open engineering group that writes internet standards
• RFC — a numbered, public, permanent standards document

Deliberately not covered yet

Recorded so future lessons do not silently assume them:

• ports
• DNS
• routing
• TCP / UDP
• HTTP / HTTPS / TLS
• subnets and CIDR notation (/8, /24)
• NAT — the translation mechanism referenced above, not yet explained
• firewalls
• AWS, Docker, Kubernetes, proxies, load balancers, ingress

Sources

Every factual claim above can be verified here.

Primary standards documents

Address exhaustion

IPv6 adoption

IPv4 resale market — indicative only

Source note: the RFC and registry links are authoritative primary sources. The resale-market links are commercial brokers and analysts — useful for order of magnitude, not precise figures.

End of Lesson 01. Next: ports.