What Is IPv6? Differences from IPv4 and How to Prepare Your Website

What is IPv6 and what does it do?

IPv6 is the sixth version of the Internet Protocol, and it uses 128-bit addresses. It gives every device and server a unique address so they can find each other on the internet. Engineers designed it because IPv4's 32-bit address space was running out, and it also simplifies some routing and setup tasks.

For a website owner, the "what is IPv6" question comes down to this: visitors reach your site over either an IPv4 or an IPv6 address. So the addresses your domain resolves to affect who can connect and how smoothly.

In this guide we answer the "what is IPv6" question without drowning you in jargon. Then we cover how to write addresses, how dual stack works, what an AAAA record does, and which steps get a website ready.

Everything here rests on official documents: IETF RFC standards, IANA registries and Google's own documentation. We are a digital marketing and web team, not a hosting company. For that reason we lean on those sources rather than claiming first-hand server operations.

How does IPv6 differ from IPv4?

Once you have the "what is IPv6" answer, the comparison is easy: both protocols do the same basic job. However, they differ in address length, notation and some configuration mechanics. The table below sums up the main differences, and the sections after it explain each one.

The header and fragmentation rows come from RFC 8200. In short, IPv6 is not just a longer address; it also streamlines how the protocol works.

Why is the IPv6 address space so large?

An IPv4 address has 32 bits, so it offers 2 to the power of 32 addresses, roughly 4.3 billion. That is far fewer than the number of connected devices, so IPv4 ran short. IPv6 uses 128 bits, so it defines 2 to the power of 128 addresses.

That works out to about 3.4 times 10 to the power of 38. However, the number has no everyday equivalent. What matters is that address scarcity goes away, so giving a server or device its own public address is no longer wasteful.

Also, a side effect of this abundance is subnet size. A standard IPv6 subnet uses a 64-bit prefix. In other words, a single subnet holds more addresses than the whole IPv4 internet. So you do not ration addresses in IPv6; you plan the network around order and simplicity.

The abundance also reduces the need for NAT. For example, NAT hides many devices behind one public IPv4 address. With IPv6, each device can have its own address. That does not mean every device should be reachable from the internet, though. Firewall rules stay in your hands.

How do you write an IPv6 address?

An IPv6 address has eight groups separated by colons. Each group holds up to four hexadecimal digits. RFC 5952 standardizes the text form, so everyone writes the same address the same way.

Three rules matter, and we take them in order. First, drop the leading zeros in each group. Second, replace the longest run of all-zero groups with a double colon. Third, write the letters a to f in lowercase.

Full form : 2001:0db8:0000:0000:0000:0000:0000:0001
Short form: 2001:db8::1

A double colon can appear only once in an address. Otherwise nobody could tell how many groups it skipped. Also, RFC 5952 says you should not use a double colon to shorten a single zero group.

Also, inside a URL you wrap the address in square brackets. For example, you type http://[2001:db8::1]/ in the browser. The reason is that the brackets keep the colons in the address from clashing with the port number.

Every example address in this article comes from 2001:db8::/32. That block exists for documentation only and does not belong to a real network.

What types of IPv6 addresses are there?

The first bits of an IPv6 address tell you its type. As a site owner you do not need to memorize them. Still, recognizing an address on sight saves time when you debug a configuration.

According to the IANA registry, global unicast assignments currently stay within the 2000::/3 range. So the public addresses you see online usually start with a 2 or a 3.

Also, every IPv6 interface creates a link-local address on its own. You never publish those in DNS, because nobody outside the link can reach them.

Why did the move to IPv6 come up in the first place?

The main reason is address scarcity. In practice, the IPv4 pool shrank, and getting new addresses became harder and more expensive. Therefore networks turned to NAT layers, address leasing and more complicated setups.

Google continuously measures how many of its users reach Google over IPv6 and publishes the result on its statistics page. Also, the page says the data is meant for internet providers, website owners and policy makers. Check it for the current share; we do not quote a fixed figure, because it keeps changing.

If you wonder what IPv6 means for your own site, think about your visitors. Some of them may connect through an IPv6-only or IPv6-first network. Then, if your site misbehaves on those addresses, they may see a slow or broken experience.

However, there is no need to panic. IPv4 still works, and if your site answers over IPv4, most visitors connect without trouble. Adding IPv6 is a gradual preparation task rather than an emergency.

What is dual stack and how does it work?

Dual stack means a device or server runs IPv4 and IPv6 at the same time. RFC 4213 describes this approach as a transition mechanism. For that reason it is the path most often recommended for websites today.

With dual stack, your domain has both an A record and an AAAA record. Then the client sees two kinds of addresses in the DNS answer. Its operating system and network decide which one to try.

This is where the Happy Eyeballs algorithm steps in. RFC 8305 describes how a client tries both address families almost in parallel. The standard recommends a default connection attempt delay of 250 milliseconds. As a result, if the IPv6 path is broken, the user falls back to IPv4 without a long wait.

The mechanism helps you, but it can also mask a broken IPv6 record. Your site may not feel slow, yet the AAAA record may still point to the wrong address. So after you set up dual stack, test both paths separately.

Which other transition methods exist between IPv4 and IPv6?

Dual stack is not the only option. For example, network operators use other methods depending on their needs. Most of these are decisions for your hosting provider or internet provider, not for you.

• Tunneling: carries IPv6 packets across an IPv4 network. It works as a stopgap on a network that offers no IPv6.
• NAT64 and DNS64: let IPv6-only clients reach IPv4 servers. RFC 6146 and RFC 6147 define these mechanisms.
• IPv6-only networks: some operators give clients only IPv6 and provide IPv4 access through these translators.

As a site owner you do not need the translation details, because those belong to the network. Still, one point is enough: your IPv4 address should keep working, and IPv6 should be an added path.

That way you reach visitors on both older and newer networks. Offering IPv6 alone would add needless risk today.

What is an AAAA record and how does it differ from an A record?

An AAAA record is the DNS record that maps a domain name to an IPv6 address. RFC 3596 defines this record type. An A record, by contrast, does the same job for an IPv4 address.

You can define both an A and an AAAA record for one domain. Also, your DNS panel shows them as separate rows. Before you add the AAAA record, make sure your server really answers over IPv6.

The reason is simple. Because the moment the record goes live, visitors on IPv6 start going to that address. If nothing listens there, they get a connection error. You can check your records with our DNS lookup tool.

What is IPv6 and does it affect SEO rankings?

The short answer: there is no official evidence that IPv6 support alone gives a ranking boost. Google's page experience documentation covers Core Web Vitals, HTTPS, mobile friendliness and intrusive interstitials, and it does not mention IPv6. It also stresses that there is no single signal.

So treat any promise like "move to IPv6 and rank higher" with suspicion. Whoever makes that promise is not relying on an official source.

On the other hand, indirect effects can exist. If your site fails on some network because of IPv6, both visitors and crawlers run into trouble. A bot cannot crawl a page it cannot reach, and an uncrawled page struggles to show up in results.

So the accurate statement is this: IPv6 is not a ranking trick, but a misconfigured IPv6 setup can cause access and crawling problems. As part of a technical SEO check, confirming that the setup works is enough. For the wider picture, see our technical SEO tips.

Are the common IPv6 speed and access myths true?

Some claims about IPv6 are exaggerated. So do not decide without measuring. The table below puts common claims next to what the evidence supports.

Still, let us be honest about speed. On some networks the IPv6 path is shorter, on others it is longer. A source that promises a general speed gain without showing measurements is not reliable.

For your site's real speed, look first at server response time and page weight. We cover this in our article on site speed and SEO.

How does IPv6 affect firewalls, bots and log analysis?

When you enable IPv6, you manage two sets of security rules. Firewall rules you wrote for IPv4 do not cover IPv6 traffic automatically. In fact, many tools keep a separate rule set for each protocol.

So anyone who turns on IPv6 should review the firewall for IPv6 too. Otherwise a port that is closed on IPv4 can stay open on IPv6. For example, if you use ufw, confirm that the IPV6 option in /etc/default/ufw is on.

Log and analytics tools also feel the change. A script that assumes the IPv4 format may parse IPv6 addresses incorrectly. Also, if your bot filters and allowlists contain only IPv4 ranges, they will miss legitimate requests that arrive over IPv6.

Google publishes Googlebot IP ranges as JSON files in CIDR format. It also recommends that you verify an IP with a reverse DNS lookup. Therefore the same logic works for IPv6 addresses, as long as your tools recognize them.

What is IPv6 and what should online stores check?

In e-commerce, an IP address is more than a network detail. Many security and integration rules depend on it, so check them first. So before you enable IPv6, list which rules rely on addresses.

• Rules that let only certain IPs into the admin panel.
• Rules that filter payment or shipping notifications by IP.
• Rate limiting and bot protection that count requests per address.
• Fraud prevention and country detection plugins that use the IP.

Each of these rules must understand IPv6 addresses. If one does not, it either blocks a legitimate customer or quietly stops protecting you. Also, ask your provider whether it publishes its notification address list for IPv6 too, and read its documentation for the answer.

However, rate limiting has one more catch. A standard subnet uses a 64-bit prefix, so one user can hold a whole block instead of a single address. A limit that looks at one address is therefore easy to get around. Check your security tool's documentation for how it handles this.

In short, for a store owner the practical answer to the "what is IPv6" question goes like this: a new address type, and every rule that ignores it is a risk. To avoid breaking the order flow, try the change in a test environment first. We covered the link between speed and sales in our ecommerce page speed article.

How does IPv6 affect email delivery?

Email is the area people forget most often during an IPv6 move. Opening your website to IPv6 may not touch your mail server. However, if one server runs both the site and the mail, you must think about the settings together.

If the sending server goes out over IPv6, check three records. First, authorize that address in your SPF record with the ip6 mechanism. Second, define a reverse DNS record for that address. Third, make sure your email signing setup works the same on both paths.

Because of this, if one of these is missing, receiving servers may treat your messages as suspicious. For example, you might list only the IPv4 address in SPF while mail leaves over IPv6, and that can trigger authentication failures. Worse, you usually do not notice; you just hear that messages land in spam.

If you do not want to risk deliverability, handing email to a dedicated provider is a reasonable choice. In that case, apply the SPF and other records from the provider's instructions as given. Running your own mail server is a separate specialty and outside this article.

How do you prepare your website for IPv6?

The order of steps matters. First you confirm the infrastructure offers IPv6, and then you add the DNS record. If you reverse the order, visitors get sent to an empty address.

1. Check whether your hosting or VPS provider gives you an IPv6 address.
2. Confirm that the server has the IPv6 address configured.
3. Make sure the web server listens on IPv6.
4. Open the needed ports for IPv6 in the firewall.
5. Check that the SSL certificate covers your domain name.
6. Finally, add the AAAA record in DNS.
7. Wait for the record to propagate, then test both address families.

Also, going step by step makes it easier to find where an error sits. Also, taking a backup before you touch DNS is a good habit. For your backup routine, see our website backup strategy guide.

For example, on shared hosting the provider handles most of these steps for you. You only enter the AAAA record in the panel, or the IPv6 address the provider gives you.

Which commands check IPv6 support on your server?

If you manage your own VPS, a few commands give you a clear picture. The examples below are for Linux. Also, the domain and addresses are placeholders, so use your own values.

# List the IPv6 addresses configured on the server
ip -6 addr show

# See which addresses the web server listens on
ss -ltn | grep ':443'

# Query the AAAA record of a domain
dig +short AAAA example.com

# Request HTTP headers over IPv6
curl -6 -I https://example.com

# Try IPv4 as well, for comparison
curl -4 -I https://example.com

The first command shows which IPv6 addresses sit on your interfaces. The second tells you whether the server listens on port 443, and whether it does so for IPv6. In practice, a listening line with square brackets is the sign of IPv6.

Then the third command tells you whether an AAAA record exists. Finally, the last two prove that each path works on its own. If one fails, the problem sits in exactly that address family.

If you prefer a ready-made interface, our IPv6 test tool runs the same kind of check without any typing.

How do you enable IPv6 in Nginx and the firewall?

In Nginx you define IPv6 listening with the listen directive. The official examples write addresses in square brackets. Our server block below is only an example, so use your own certificate paths and domain.

server {
    listen 80;
    listen [::]:80;
    listen 443 ssl;
    listen [::]:443 ssl;
    server_name example.com www.example.com;
    # certificate and other settings go here
}

The logic is simple, because you write a separate listen line for each protocol. Lines with brackets answer IPv6 requests, and the plain lines answer IPv4 requests.

After the change, test the configuration and reload the server. Run nginx -t, and if the result is clean, reload the service. If you get an error, you can fix it without touching the running setup, because a failed reload leaves the old configuration active.

The same logic applies to the firewall. Open the HTTP and HTTPS ports for IPv6 as well. Depending on your tool, that means a separate rule line or a separate setting. Do not write rules before you read your own tool's documentation.

What mistakes come up most often during an IPv6 move?

Most problems in a move gather around the same few spots. You can use the list below as a checklist.

• Adding an AAAA record while the server does not listen on IPv6.
• Configuring the firewall for IPv4 only.
• Leaving a wrong or old IPv6 address in the AAAA record.
• Forgetting to remove the old AAAA record after moving the server.
• Mixing up the origin server's IPv6 status when you use a CDN or proxy.
• Missing that your log and analytics tools do not recognize IPv6 addresses.

Forgetting the old address record after a move is one of the most common slips. You update the IPv4 record, but the AAAA row quietly keeps pointing at the old server. As a result, some visitors land on the old machine.

Email needs its own care, as the previous section showed. If you add IPv6 to an existing domain, review SPF and reverse DNS in the same session so nothing slips through.

Should you set up IPv6 yourself or leave it to your hosting provider?

For most site owners, the right answer is to leave it to the provider. On shared or managed hosting, IPv6 support is the provider's job. You only take small steps such as adding an AAAA record.

If you want to manage your own VPS, the commands are simple enough. However, the responsibility is yours. A wrong firewall rule can make the site unreachable, or it can open a port you did not mean to open.

Do not do it yourself, and leave it to your provider, in these cases:

• You use managed or shared hosting.
• You cannot risk losing remote access to the server.
• You run a live online store without a test environment.
• Network configuration, such as routing or subnets, is new to you.

In these cases it is enough to ask the provider: "Can our server get an IPv6 address, and how do we enable it?" The support team often sends you the address and the needed setting. If you are still choosing, our web hosting selection guide helps you add IPv6 support to your criteria.

How do you run an IPv6 test and read the results?

A test should answer two questions. Does your domain have an AAAA record? Does that address really respond? IPv6 is not ready until both answers are yes.

The "what is IPv6" answer is half the job, and testing is the other half. Check the DNS side first. If no AAAA record appears, your site does not serve IPv6 yet. That is not an error; it only shows that you have no IPv6 support.

If a record exists, the connection is next. Try to reach the site over IPv6 and confirm the certificate is valid. The SSL checker shows certificate details, and we explain certificates in our SSL certificate article.

If you wonder who owns an IP address, use the IP lookup tool. To see which address your own connection uses, the what is my IP page shows it.

Read the results this way: a missing AAAA record is just information. An AAAA record with no working connection is a bug you need to fix. You fix it either by correcting the address or by deleting the wrong record.

After a move, what should you monitor?

A move is not something you do once and forget. As long as the AAAA record is live, the IPv6 path of your site is your responsibility. So you need to add a second path to your monitoring routine.

• Confirm that your uptime monitoring checks IPv4 and IPv6 separately.
• Look at error rates from IPv6 addresses in your server logs.
• Update the AAAA record whenever you migrate the server or change an IP.
• Retest both paths after you renew the SSL certificate.

Many simple monitors query only the domain name and do not show which address family they used. So even when the IPv6 path breaks, the dashboard can look green. To catch this, check your monitor's settings and, if needed, add a task that checks the address directly.

The crawl statistics in Google Search Console also help. If you see a rise in server errors or connection problems, include a broken AAAA record among the possible causes. For a broader look at technical health, read our Core Web Vitals guide.

What is IPv6 in practice, and when should you act?

For most small business sites, IPv6 is not an urgent requirement. However, preparing makes sense for sites that run their own infrastructure, draw heavy traffic or get many visitors from mobile networks.

Weigh a few criteria. If your provider already offers IPv6, switching it on costs very little. If you build infrastructure from scratch, planning dual stack from the start is easier than adding it later.

In short, here is the practical answer to what IPv6 is: an internet protocol that goes beyond IPv4's address limit and works alongside IPv4 today. It is not a ranking trick, yet it widens access when you set it up right, and it causes silent errors when you set it up wrong.

If you want us to review your site's technical foundation together with its SEO structure, our SEO consulting and web design services cover that. For infrastructure decisions, we suggest working with your hosting provider's technical team.

Which official sources can you read for more detail?

The technical statements in this article rest on the primary sources below. If you want the detail, go straight to these documents.

• RFC 8200: the IPv6 protocol specification.
• For writing rules, see RFC 5952: the recommended text form of IPv6 addresses.
• For DNS, see RFC 3596: DNS extensions for IPv6 and the AAAA record.
• IANA IPv6 address space registry: prefix assignments.
• Google IPv6 statistics: the share of users reaching Google over IPv6.
• Google page experience documentation: the experience factors that matter for ranking.

The IETF sometimes replaces an RFC with a newer one. So before any critical configuration, check the document's current status.