So… Where Did All the IPv4 Go? The Real Story Behind Exhaustion and Price Surges

It started with a tiny line on a client’s invoice. Not the CPU, not the storage, not even the bandwidth. A few bucks tagged onto every server for “IPv4 rental.” At first it felt harmless—coffee money. Then a couple more apps came online, one more region spun up, a staging environment for a big launch, and suddenly that tiny line had multiplied into a real number. The team messaged me late on a Wednesday: “Are we seriously paying that much just for IPs?”

Ever had that moment when something you never used to think about quietly becomes the most expensive part of your hosting bill? That’s the IPv4 story in 2025. We’ll talk about why IPv4 addresses are scarce, what’s pushing prices up, the trade‑offs that surprise people (reputation and compliance are sneakily important), and the calmest path forward. I’ll share some real‑world things I’ve tried—stretching a small pool of IPs without breaking SSL, making mail deliverability behave, and rolling out IPv6 without turning Friday night into a fire drill.

Here’s the thing: IPv4 Exhaustion and Price Surges aren’t just headlines. They show up in architecture diagrams, in the way we design our apps, and yes, in the invoice line nobody noticed last year.

Okay, but what does “exhausted IPv4” actually mean?

Think of IPv4 addresses like phone numbers in a small town. For decades, there were enough numbers for everyone. Then the town grew, the suburbs exploded, and suddenly every gate had a smart intercom. We didn’t “break the system,” we simply ran out of numbers that fit the old pattern. That’s IPv4. The central pools were divvied up to regional registries, who handed them out to providers, who passed them to customers. Eventually, the central pool ran dry. That didn’t mean no one had IPv4 anymore—just that there was no fresh supply to allocate.

From there, the only way to get new IPv4 blocks was to buy or lease them from someone who already had some. That created a marketplace. And like any marketplace, it’s driven by scarcity, friction, and perception. I remember when a small /24 block felt easy to pick up and relatively cheap. Today, those same blocks trade like city parking spaces—always in demand, never quite enough, and worth more than you’d assume for such a small rectangle.

If you want the official backstory, skim IANA’s note on the final IPv4 allocations. It’s not drama for drama’s sake—just a clear marker that the faucet is off and the buckets are being passed around.

Why are IPv4 prices surging? The quiet factors no one mentions first

Scarcity is the headline, but it’s not the whole movie. In my experience, five drivers make the price arc feel relentless. First, the easy blocks are gone. What’s left is scattered, sometimes messy in reputation, and frequently in sizes that don’t match what teams want. Second, policies and paperwork add friction. Transfers between regions, audits, and “show me your usage plan” steps don’t block deals, but they slow them down and add cost. Third, reputation has become part of the price. A clean block that isn’t tangled in blacklists or ancient router leaks can command a premium, especially if you send mail or run ads.

Fourth, applications aren’t rebuilt overnight. The internet speaks both IPv4 and IPv6, but lots of systems still assume IPv4 for comfort, constraint, or just the “no time this sprint” reality. That inertia keeps demand high. Fifth, demand is spiky. A new product launch, a cross‑region push, or a compliance requirement that wants an address per tenant—these moments make teams buy now and ask optimization questions later. Scarcity plus urgency multiplies price pressure.

The result isn’t always dramatic on day one. It’s more of a slow boil. Extra charges per IP appear across environments. Providers start rationing or pricing blocks in ways that nudge you toward NAT. And because no one wants downtime, teams pay the premium and promise themselves they’ll optimize next quarter. I’ve said that line, too.

Where the IPv4 bill hides in your stack

In a typical hosting setup, IPv4 costs hide in a few unglamorous corners. The most obvious is direct allocations for servers, load balancers, or firewall IPs. A surprising one is outbound services. If you handle mail, a dedicated IPv4 is almost a rite of passage, not just for isolation but for reputation management and traceability. That IP becomes your calling card in inbox land, and yes, it’s worth protecting.

Then there’s the shape of your architecture. I’ve seen teams hand out dedicated public IPv4s like party favors to every internal service that might someday need external access. It feels safe until the bill rolls in. A calmer pattern is to put things behind a reverse proxy or load balancer, and funnel traffic through a small, well‑managed set of public addresses. Internally, your services can live on private networks, and you get flexibility without scattering addresses everywhere.

Another sneaky cost is legacy assumptions. Years ago, certain setups insisted on dedicated IPs for SSL. With SNI, that’s mostly an ancient worry. But habits remain, and sometimes you’ll see a team with a big list of “these sites need their own IPs for certificates.” They often don’t. Rechecking SSL constraints can free up addresses without changing any URLs or moving workloads.

Mail remains a special case. Deliverability is still conservative, and having a known, warmed‑up IPv4 helps. If you’re debating whether to share or isolate, I usually push for isolation for serious mail, but with disciplined monitoring and slow, intentional ramp‑ups. It’s not just about avoiding blocks; it’s about teaching receiving servers that you are who you say you are.

A calm playbook to stretch a small IPv4 pool

I like to start with architecture because it’s where the biggest wins hide. Concentrate ingress behind a few public IPv4s using a load balancer or reverse proxy. Internally, keep services on RFC1918 private ranges and let them talk to the outside world through egress NAT. This not only reduces your public address footprint, it also cleans up security rules and logging. When you have fewer doors, you can guard them properly.

On the web layer, combine name‑based virtual hosting with SNI so dozens or hundreds of domains can share the same public IPv4 without ceremony. Modern clients handle this gracefully. Certificates don’t need to be a tangle either. If you’re curious how to do this without drama, I wrote about a clean, IPv4‑light load balancing stack that handles TLS passthrough and rolling updates without downtime. The gist is: keep the number of public IPs low, keep the proxy layer smart, and let your app teams deploy without touching addressing.

For outbound traffic, centralize egress. A small set of NAT gateways can serve a whole fleet, and with good observability you won’t lose track of who did what. I’ve seen teams fear NAT because of debugging nightmares from the old days. Tooling is kinder now. Tag connections, keep flow logs, and you gain more clarity than you had scattering public IPs everywhere.

Then there’s mail. If deliverability is mission critical, dedicate your IPv4s, but don’t throw addresses at the problem. Warm slowly, keep your sending consistent, and protect those IPs like your good name. Keep PTR/rDNS clean, watch feedback loops, and don’t be afraid to move heavy marketing sends to a provider that lives and breathes deliverability while you keep transactional mail in‑house. That balance can save IPs and time.

Finally, audit. I once reclaimed an entire /26 just by asking why certain boxes had public addresses. Half of them were “temporary” debug ports from last year. The rest were internal tools that never needed to be on the edge. You’ll be amazed what a friendly inventory round will uncover.

Leasing vs buying: the practical checklist no one hands you

When you step into the market, treat IPv4 like real estate. Location matters, history matters, and paperwork matters. Make sure the block’s reputation is clean. That means checking common mail blocklists and asking about prior use. I once saw a company inherit carbon‑dated blacklisting baggage because the block had been part of an old botnet range. They spent weeks untangling it. Pay the small premium for clean, or budget time for cleanup—it’s one or the other.

Validate the route story. Ask about ROAs and RPKI status in plain language: can this be announced cleanly without you getting caught in someone else’s leak? Confirm the authorization path—LOA or whatever your provider requires—and that the chain of custody is clear. Watch out for gotchas like mismatched WHOIS or stale geolocation. That last one sounds minor until your Turkish users get mapped to Toronto for a month and your ads go sideways.

If you’re operating in North America, give ARIN’s transfer process overview a skim before you talk to a broker. It helps set expectations on documents and timelines. The same logic applies in other regions: read the basics once, skip a week of email back‑and‑forth later.

Should you lease or buy? It depends on how durable your need is. If this is a short‑term spike or an experiment, leasing can be perfect. If you know you’ll need the addresses for years, buying gives you control and sometimes lowers your long‑run cost, though you’ll carry the responsibility for management, announcements, and reputation. If a cloud provider supports BYOIP, bringing your block can simplify consistency across regions and platforms, but don’t gloss over the operational chores. Ownership feels great until you have to respond to an abuse ticket on a Sunday morning.

The IPv6 path that actually sticks

Let me share a small win. A client wanted to shave IPv4 costs but was nervous about breaking users. We enabled dual‑stack on the edge, created AAAA records, and tested the rollout behind a feature flag. No fireworks. Traffic steadily shifted to IPv6 where available, which lowered connection counts on the IPv4 side and made capacity planning saner. The biggest surprise for the team wasn’t performance; it was how quiet the change felt when done carefully.

The beauty of dual‑stack is that it’s almost invisible to users when you do it right. Modern systems use a technique often called Happy Eyeballs to prefer the fastest path without punishing slower setups. You give clients a choice, and they take the better route. On the server side, enabling IPv6 on web and API layers is usually straightforward. Certificates cover both, your app barely notices, and you get to stop paying for every new IPv4 you thought you needed.

Content delivery helps too. Many CDNs terminate on IPv6 and backhaul to your origin however you prefer. If you’ve been hesitating, read a gentle primer like Cloudflare’s plain‑English primer on IPv6 and then flip it on in one low‑risk environment. Watch your graphs. If you’ve got a global audience, you’ll see more IPv6 traffic than you expect, especially on mobile networks.

Now the honest part: email is still the cave. Plenty of receiving systems accept IPv6, but the culture around reputation and filtering remains rooted in IPv4. My rule of thumb is dual‑stack where possible, but always keep an IPv4 path for mail until your partners, providers, and metrics say otherwise. For web, APIs, and user traffic, though, IPv6 is the present—not just the future.

Operational hygiene that saves real money

I once inherited a fleet with a noble but expensive policy: “Give everything a public IP because it’s easier to reach for support.” What it really did was make firewall rules a mess and the invoice bloated. We put a jump host in place, tightened up bastion access, and turned off most of those public addresses. The support team didn’t miss a step, and we shaved a line item that looked small until you multiplied it by dozens of machines.

DNS is another quiet lever. When you renumber, set short TTLs ahead of the move, do a tidy cutover, and then restore longer TTLs. For mail, always update PTRs in lockstep with A records; mismatched reverse is the quickest way to upset spam filters. Geolocation updates matter more than people think, especially if you serve content or payments that behave differently by region. It’s a small ticket to open, a big headache to avoid.

Keep an eye on abuse queues. Sometimes one compromised service can poison an IP’s reputation faster than you’d believe. Rate limiting, sane outbound policies, and alerting on odd traffic patterns are your friends. The cost of keeping a clean house is always lower than the cost of cleaning up after a mess, especially when IPv4 is precious.

What I’d do if I were starting today

I’d begin with a tiny, high‑quality pool of IPv4s and a clear plan for where they live: edge entry points, mail, and a few special‑purpose cases that truly need them. Everything else goes private with egress NAT. I’d turn on IPv6 on day one, not because it’s trendy, but because it reduces pressure on the IPv4 side and future‑proofs the surface I’ll have to touch in a year.

For sending mail, I’d isolate transactional and marketing traffic and warm addresses slowly. I’d keep my reverse DNS squeaky clean and automate as much as I can so mistakes don’t sneak in at 2 a.m. On the web front, I’d consolidate domains onto shared front doors with SNI, and keep my certificates organized without over‑allocating IPs. I’d monitor blocklists as a routine, not a crisis drill, so surprises stay small.

When it’s time to expand, I’d evaluate leasing first if the need is short‑lived, and buying only when I’m sure. Before any transaction, I’d verify the routeability, the paperwork, and the history. And I’d write down the runbook for renumbering and cutovers so the team isn’t guessing under pressure next time.

A few things that feel counterintuitive (but work)

Sharing works better than you think. The instinct to dedicate a public IPv4 to every domain or microservice is strong, but it’s rarely necessary. SNI lets you collapse many front doors into one. A single, well‑designed load balancer pair can do the work of a dozen small edge points. And when you do need to spread across regions, bring discipline, not sprawl: repeat the pattern cleanly rather than improvising another handful of IPs “just for now.” We both know “just for now” becomes forever.

NAT isn’t the villain. The bad old days of ugly logs and finger‑pointing are fading. With flow logs, connection tagging, and modern observability, NATed fleets can be easier to reason about than a sea of public IPs. The egress points become security and compliance checkpoints, which simplifies audits too.

IPv6 adoption isn’t an all‑or‑nothing move. It’s perfectly fine to enable dual‑stack on the edge, watch traffic shift, and take the wins as they come. Your team will gain confidence, your metrics will show the real picture, and you’ll be spending less time hunting for extra IPv4s that you didn’t really need.

The money conversation you’ll actually have with your team

At some point, someone will ask, “Can we cut this IPv4 line item in half?” The honest answer is often yes, but it’ll come from design, not haggling. Start with a map: which services truly require a public IP, and which can move behind the edge? How many mail streams deserve isolation? Which environments still carry legacy allocations they don’t use? When you convert those answers into architecture changes, the savings show up in the next billing cycle—without sacrificing reliability.

The flip side is recognizing places where spending is justified. If your business depends on email landing in inboxes, a clean, dedicated IPv4 is cheap compared to lost revenue from poor deliverability. If your security posture benefits from purposeful separation, that’s money well spent. The trick is to be intentional, not casual, with every address you hold.

One last resource trio if you want to go deeper

For background on how we got here, I still point folks to IANA’s note on the final IPv4 allocations. If you’re eyeing the transfer market in North America, ARIN’s transfer process overview is worth a look before you email brokers. And if you want a friendly explainer your teammates won’t dread, Cloudflare’s plain‑English primer on IPv6 is a great nudge to finally flip the switch.

Wrap‑up: the calm path through IPv4 Exhaustion and Price Surges

When that invoice line first stings, it’s tempting to blame the market and move on. But there’s a calmer path. Start by shrinking your public surface: put services behind smart edges, share IPv4s aggressively with SNI, and centralize egress. Protect the IPs that matter, especially for mail, and keep their reputation pristine. When you need more addresses, treat the market like real estate—check the neighborhood, the paperwork, and the history before you sign.

Then give yourself breathing room by turning on IPv6 where it makes sense. Dual‑stack is not a personality test; it’s a practical way to reduce pressure on your IPv4 pool and future‑proof your stack. With a few careful steps, the price conversation becomes easier, the architecture gets cleaner, and those “temporary” exceptions stop piling up.

Hope this was helpful. If this sparked ideas or you want to swap stories about reclaiming runaway IP allocations without breaking production, I’m all ears. See you in the next post—and may your PTRs always match your A records.