IP address: what it is, IPv4 vs IPv6, and how they relate to domains

When you open a website, send an email, or connect to a server, the network needs to “know” where to deliver the data and where to send the response back. This is what IP addresses are for – unique network identifiers of nodes on the Internet.

Domain names make life easier for people: instead of remembering numbers, you enter a clear name, for example site.ua. Then DNS converts this name into the server’s IP address, and the connection is established using that address. That is why IPv4 and IPv6 are always mentioned alongside domains, DNS, and hosting: these are two versions of the addressing protocol that define the format and capabilities of IP addresses.

What is an IP address?

An IP address (Internet Protocol address) is a unique address of a device or server on a network, used by routers to deliver data packets to the correct recipient. In simple terms, it is the “coordinates” of a node on the Internet. When you enter a domain in a browser, DNS finds the IP address, and the request is sent to that address – this is how the network understands exactly where to connect.

A port works separately from the IP address. It is the number of a specific service inside a node. IP answers the question “where to go”, while the port answers “which service to contact”. The same server may have one IP address but serve many different services: web, email, SSH on different ports. For web traffic, the most commonly used ports are 80 (HTTP) and 443 (HTTPS), while SSH usually uses port 22.

IP addresses are assigned and managed at different levels: in a local network, they are usually distributed by a router automatically via DHCP, while public addresses are assigned by an Internet provider or hosting provider for servers, VPS, and dedicated machines. In hosting, an IP address is important not only for website access, but also for the correct operation of infrastructure-related tasks: server management, DNS record configuration, SSL/TLS, email reputation mechanisms, and more.

Most often, IP addresses are divided into the following types:

• public – visible on the Internet and used for servers and hosting, and private – used only in local networks and connected to the outside world through NAT;
• static – fixed and unchanged, and dynamic – able to change over time or after reconnection.

The format of the address itself and the rules for using it are defined by the protocol version: IPv4 or IPv6. The version determines what the address looks like, how many such addresses can exist, and which network capabilities are available by default.

What is IPv4?

IPv4 (Internet Protocol version 4) is the fourth version of the Internet Protocol, which defines the rules for addressing and delivering packets across a network. For decades, IPv4 has been the foundation of the Internet and is still the most common IP address format for websites, servers, and provider networks.

IPv4 uses 32-bit addressing, which means the total number of possible unique addresses is limited to approximately 4.3 billion. The address is written as four numbers from 0 to 255 separated by dots, for example: 203.0.113.10 or 192.168.0.1. In the context of hosting and domains, this means that a domain in DNS most often points to an IPv4 address through an A record, and the browser connects to the server using that address.

The problem with IPv4 is that it was created at a time when no one predicted the modern scale of the Internet: billions of smartphones, IoT devices, virtual machines, containers, and cloud services. As a result, free public IPv4 addresses eventually became a scarce resource, and networks began to widely use address-saving techniques. The best-known of them is NAT.

Characteristics and limitations of IPv4

IPv4 is a mature and highly compatible protocol: it is supported by almost all network equipment, operating systems, and provider networks. That is why it still dominates the Internet, and for hosting and domains it remains the default option: most websites have an A record in DNS pointing to the server’s IPv4 address.

The key technical features of IPv4 were shaped historically. The protocol allows packet fragmentation along the route: routers can split a packet if it does not fit the MTU. It uses ARP to determine MAC addresses in a local network segment, while address configuration is done manually or through DHCP. For many scenarios, this works reliably, but it adds layers of logic to the infrastructure and makes large or dynamic networks harder to maintain.

The main limitation of IPv4 is the shortage of address space. 4.3 billion may sound like a lot, but the number of public addresses is much smaller due to reserved ranges and historical allocation rules, while the number of devices and services keeps growing. That is why NAT is widely used, allowing many devices in a local network to access the Internet through a single public address.

For the user, this is usually invisible, but for infrastructure, NAT often becomes a source of complexity: it breaks the end-to-end principle, complicates transparent routing, makes direct inbound connections harder to organize, and forces some services to use additional configuration or workarounds.

Another practical disadvantage is that security is not built into IPv4 as an integral part of the protocol. Traffic protection is usually implemented on top of the protocol or alongside it: VPN, TLS, optional IPsec, firewall, and other tools. This requires additional architecture and control. IPv4 also historically uses broadcast mechanisms in local networks, which can create unnecessary load in large segments.

IPv4 works reliably, but as a platform for growth it has long been close to its limits: the Internet relies on a scarce address resource and compromises such as NAT. This became the main reason for the emergence of IPv6.

What is IPv6?

IPv6 (Internet Protocol version 6) is the next version of the Internet Protocol, created as a long-term replacement for IPv4. Its main purpose is to eliminate the shortage of addresses and introduce modern principles of network operation: simpler routing, better scalability, and a proper end-to-end architecture without constant dependence on NAT.

IPv6 uses 128-bit addressing, so the available address space has practically no real limitations for the future development of the Internet. The address is written in hexadecimal format, divided into blocks, for example: 2001:db8:85a3::8a2e:370:7334. The notation can be shortened: sequences of zeros are compressed using ::, and leading zeros in blocks are omitted. This makes the addresses more readable, although they are still longer than IPv4 addresses.

In combination with domains, IPv6 works as logically as IPv4: a domain name in DNS can point to a server’s IPv6 address through an AAAA record. If the client, such as a browser, application, or bot, and the network support IPv6, the connection will be established directly over IPv6. If not, IPv4 or compatibility mechanisms in the infrastructure are used. This explains why dual stack is often configured today, when the same service is available over both IPv4 and IPv6.

Characteristics and limitations of IPv6

IPv6 was designed as a protocol for a large, dynamic Internet where addresses should be available with a huge reserve and the network should be easier to route and scale. Compared with IPv4, it has a different design logic: fewer historical layers, more focus on efficiency and automation.

The key characteristics of IPv6 include:

1. Large address space (128 bits): there are enough addresses for clouds, containers, IoT, and future growth without having to “save” addresses at every step.
2. SLAAC (stateless autoconfiguration): devices can receive an address automatically without classic DHCP as the only mechanism.
3. No broadcast: multicast is used instead, which reduces background traffic in network segments.
4. Fragmentation is performed by the sender, not by routers: routers do not split packets along the route, which simplifies traffic processing.
5. Simplified packet header: fewer fields and a fixed structure reduce routing overhead.
6. IPsec support at the protocol level (optional): encryption and authentication are included in the IPv6 architecture.
7. Better support for real-time scenarios: the protocol includes mechanisms that help the network handle sensitive traffic flows more correctly.

The limitations of IPv6 are not related to its weakness, but to the reality of implementation. IPv6 is not directly compatible with IPv4, so migration requires infrastructure solutions: dual stack, tunneling, or translation. For this reason, migration in large networks often becomes a project involving address planning, security policies, hardware updates, monitoring, and team training.

Another practical issue is uneven support: some providers, corporate networks, legacy devices, and applications are still not fully ready for IPv6. As a result, IPv6 is already the standard for the future, but in the real Internet it often works alongside IPv4 rather than replacing it completely.

Key differences between IPv4 and IPv6

IPv4 and IPv6 perform the same basic role: they address nodes and ensure packet delivery across the network. The difference lies in how this is implemented. IPv4 is an older protocol with a limited address space, which is why the Internet relies on compromises such as NAT. IPv6 is architecturally newer: it has addresses with a huge reserve, fewer unnecessary mechanisms in local networks, simpler routing, and better scalability for modern infrastructure.

The difference is especially clear in practice.

The practical conclusion for domains and hosting is simple: if your domain has an A record, it points to IPv4; if it has an AAAA record, it points to IPv6. In modern infrastructure, both records are often configured so that the website is accessible both to clients using IPv6 and to those still using IPv4. This is not a choice of only one option, but a way to ensure maximum compatibility and stable access regardless of the user’s network.

Why is IPv6 better?

The main advantage of IPv6 is that it removes the fundamental limitation of IPv4: the shortage of addresses. In practice, this is not just about “more combinations”. A large address space changes the approach to network design: instead of constant saving and complex NAT schemes, infrastructure can be designed more directly, clearly, and with room for scaling.

For hosting and servers, this matters for several reasons. First, IPv6 allows unique addresses to be assigned to services, virtual machines, containers, development and testing environments without competing for every IPv4 address. Second, the end-to-end logic returns: a client can connect to a server directly, without additional address translation layers, which reduces network bottlenecks and simplifies diagnostics.

From the technical point of view, IPv6 provides more efficient network operation at large scale: it has a simplified header, fewer unnecessary mechanisms in local segments, no broadcast, and fragmentation is not shifted to routers. As a result, network equipment processes traffic more easily, and infrastructure becomes easier to automate, especially thanks to SLAAC and more logical addressing.

Another advantage is readiness for modern scenarios. Where the number of microservices, Kubernetes events, isolated environments, and temporary instances is growing, IPv6 fits more naturally into the idea that everything scales quickly and in large quantities. That is why IPv6 support on the hosting side is not just a marketing checkbox, but an infrastructure reserve for the future and a way to reduce dependence on the scarce IPv4 resource. For such scenarios, Kubernetes clusters on VMware Tanzu and proper infrastructure automation with Terraform are also important.

Which IP protocol is more secure: IPv6 or IPv4?

To be clear, no protocol makes a network automatically secure by default. The level of protection depends on how servers, firewalls, updates, network segmentation, access policies, and monitoring are configured. However, IPv4 and IPv6 have architectural differences that influence how security is built.

In IPv4, security was historically not part of the protocol itself. Encryption and authentication are usually implemented at higher levels: TLS/HTTPS, VPN, SSH, or additional network solutions. Also, due to the wide use of NAT, many inbound connections do not reach the end device directly. This is often perceived as protection, but in essence NAT is not a security mechanism – it is a way to save addresses. It may accidentally reduce the attack surface because there is no direct access, but it can also hide architectural problems and make traffic control more difficult.

In IPv6, IPsec support is included in the protocol architecture. An important nuance: this does not mean that all IPv6 traffic is automatically encrypted. IPsec usually needs to be configured, while in real web scenarios encryption is still handled through TLS. However, the protocol’s readiness for end-to-end protection is an advantage, especially in corporate scenarios and networks with clear policies.

There is another side as well. Since IPv6 does not require NAT, nodes more often receive globally routable addresses, which means they can theoretically be more visible from the outside. This is not a problem if the firewall is configured correctly and unnecessary ports are closed, but it requires a disciplined approach to access policies. During the transition period, risks may also increase because of mixed infrastructure: dual stack, tunnels, and translation between IPv4 and IPv6 if they are configured carelessly.

The practical conclusion is this: security depends not on the IP version, but on the settings. IPv6 provides a better foundation for modern network architecture and includes possibilities for end-to-end protection, but it requires the same or even greater attention to firewalls, access rules, and service control as IPv4. For a systematic approach to protection, it is useful to look not at a single protocol, but at a comprehensive information security system.

Did IPv5 exist?

Yes, but not in the sense usually associated with a “successor to IPv4”. IPv5 was used as the version number for the experimental Internet Stream Protocol (ST), which was developed in the 1980s for real-time data transmission, such as streaming video or voice, with more predictable delivery characteristics. It was a separate development branch for specific tasks, not a universal replacement for IPv4 addressing across the entire Internet.

The protocol never achieved mass adoption in network equipment and software stacks. When it became necessary to create a full successor to IPv4 to solve the address shortage and network scaling problem, the number “5” was already considered taken, so the next standard was immediately assigned as IPv6.

Conclusion

An IP address is the technical foundation of any Internet connection, while domains and DNS simply make access to resources convenient for people by converting a readable name into the numerical address of a server. That is why it is critical for hosting to understand what stands behind a domain in DNS: an A record points to IPv4, an AAAA record points to IPv6, and in practice the most reliable approach today is to support both options where appropriate.

IPv4 remains the most common protocol, but its address space has long become a scarce resource, which led to compromises such as NAT. IPv6 solves this problem at the architecture level and is better suited to the modern scale of the Internet: clouds, microservices, containers, and a huge number of devices. Full transition will take time, but the direction is clear: the Internet is moving toward a model where IPv6 becomes the default standard, while IPv4 gradually turns into legacy infrastructure that will still need to be supported for a long time.