IPv4 vs IPv6: What is the difference?

In the near future, IPv6 is set to replace IPv4 as the primary internet protocol due to the impending exhaustion of unique IP addresses available for assignment under IPv4. This is because IPv4 has a limited address space that can support only up to 4.3 billion unique IP addresses, which is not enough to accommodate the ever-growing number of devices and users connecting to the internet.

IPv6 offers a solution to this problem by using a 128-bit address space that can support up to 340 undecillion unique IP addresses. This vast address space is achieved by using hexadecimal notation to represent the IP address, which allows for a greater number of unique combinations. Let’s read about it in detail in this article.

What is IPv4?

IPv4 is presently the prevalent protocol for creating, assigning, and using IP addresses. It was the initial extensively embraced version of IP addresses and operates on a 32-bit numerical addressing system, offering a capacity of approximately 4.3 billion unique IP addresses.

However, when IPv4 was developed four decades ago, its designers did not anticipate the current scenario where millions of individuals possess numerous internet-connected devices. Consequently, the limited number of IP addresses provided by IPv4 has become a significant issue.

Adding to the issue is the fact that large corporations were assigned billions of IP addresses in the early days of IPv4, and many of these addresses remain unused to this day. Furthermore, these corporations refuse to relinquish them to the world, exacerbating the shortage of IP addresses.


  • IPv4 is simple and straightforward to remember.
  • The majority of websites support it.
  • It is a well-established and proven technology, making it reliable.


  • IPv4 is facing a shortage of new addresses and resources.
  • Subnetting can become problematic due to the limited number of available IP addresses.

What is IPv6?

During the 1990s, IPv6 was developed as an upgrade to IPv4. It introduced 128-bit IP addresses, providing approximately 3.4×10^38 unique addresses. In numerical terms, this means that IPv6 offers 340 trillion trillion trillion IP addresses, which is a massive increase from IPv4’s capacity of only 4.3 billion unique addresses.


  • IPv6 operates on a 128-bit technology, offering an enormous capacity of 340 undecillion IP addresses.
  • It is a new and advanced protocol, supported by modern devices.
  • IPv6 does not present any subnetting issues.
  • The protocol’s design is more secure compared to IPv4.


  • Configuring IPv6 is more complex, increasing the likelihood of mistakes and vulnerabilities during its implementation.
  • Not all websites support IPv6.
  • IPv6 addresses are long and challenging to memorize.

What is the reason for the incomplete implementation of IPv6?

Despite the clear advantages of IPv6’s scalability, it has not been fully adopted for several reasons:

  • Incompatibility exists between IPv6 and IPv4. Hence, if a website operates only on IPv4 and a user’s device and ISP solely utilize IPv6, the user will be unable to reach the website. Accessing such a website requires the user’s device to support both IPv4 and IPv6. While most modern devices and routers support IPv6, for a smooth transition worldwide, all devices, operating systems, and ISPs need to upgrade their systems. This process might be expensive, and to prevent service disruptions, both protocols will have to run concurrently for some time.
  • The benefits of IPv6 for average users are not clear. Companies find it difficult to justify investing in new technology if their customers do not see the direct impact or value in it. The creation of more IP addresses is important for the future, but it may not have an impact on everyday users until we run out of IPv4 addresses.

What are the main differences between IPv4 and IPv6?

IPv4 and IPv6 are two protocols used for assigning unique IP addresses to devices on the internet. The main difference between these protocols is the number of bits used in the address. IPv4 uses 32 bits, while IPv6 uses 128 bits. This means that IPv6 can provide a much larger number of unique addresses compared to IPv4. There are other differences between these two protocols as well, which include changes to the address format, improvements in routing and network management, and enhancements in security features.

  1. Notation: The primary difference between IPv4 and IPv6 is their address notation. IPv4 uses a 32-bit address system represented by dot-separated decimal notation, while IPv6 uses a 128-bit system represented by colon-separated hexadecimal notation. IPv6’s larger address space allows for a significantly higher number of possible addresses.
  2. IP headers: IPv4 headers can be 20 to 60 lengthy and have variable options. IPv6 headers have a fixed size of 40 bytes and allow for extensions, making it more adaptable to future technologies. The larger IPv6 header offers advantages such as flow labels, integrity protection, and not needing to be processed in transit.
  3. Address types: IPv4 offers broadcast, unicast, and multicast addresses. In contrast, IPv6 offers unicast (global, link-local, loopback, unspecified, unique local), multicast (well-known, transient, solicited-node), and anycast addresses. IPv6’s anycast addresses require routing devices to be informed that they are sharing an anycast address.
  4. Address configuration: IPv4 addresses are usually configured manually or via DHCP, while IPv6 offers manual, SLAAC, and DHCPv6 configuration. This makes IPv6 simpler to set up and operate.
  5. Local addresses: IPv4 uses the ARP to link internet addresses to local link-layer addresses, while IPv6 uses the NDP to connect local devices to the internet gateway of the local network.

IPv4 and IPv6 similarities

Here are some similarities between IPv4 and IPv6 protocols:

  • Both IPv4 and IPv6 addresses are used to identify devices on a network and are expressed in binary format.
  • Both protocols allow for manual IP address assignment.
  • Both protocols have packet headers and support the transmission of fragmented packets.
  • Both IPv4 and IPv6 support broadcasting and multicasting.
  • Both protocols support Variable Length Subnet Masking (VLSM).

Is IPv6 better than IPv4?

The IPv6 protocol offers a range of advantages over IPv4, which include:

Enhanced Security

IPv6 is designed with security in mind and offers confidentiality, authentication, and data integrity. Unlike IPv4’s Internet Control Message Protocol (ICMP), IPv6’s ICMP packets are safer because they can use IPSec, making them less vulnerable to malware.

Global Availability

IPv6 addresses are not geographically limited, unlike IPv4 addresses that were designed with a bias towards the US. This means IPv6 addresses will be for all.

Potential for Better Routing

IPv6 has longer but consistent headers, unlike IPv4’s variable headers. This consistency could lead to simpler code for routing and less hardware processing, potentially improving user experience.

End-to-End Connectivity

IPv6 would provide enough IP addresses for all devices, making Network Address Translation (NAT) unnecessary. This allows devices to connect with internet and communicate directly with websites.


Perhaps one of the most useful capabilities of IPv6 is its stateless auto-configuration feature. This enables devices to assign themselves IP addresses without requiring a server. Instead, the device’s MAC address is used to create the IP address, which is distinct for every phone, tablet, or laptop that you own. This simplifies the process of discovering other devices connected to the same network.


Is IPv6 faster than IPv4?

It is difficult to provide a definitive answer as the adoption of IPv6 is still in progress. Although IPv6 has some performance advantages, the difference is relatively small, and IPv4 still holds a slight edge in terms of response time. A study conducted by Sucuri tested the response time of 22 domains in six different locations and discovered that IPv6 is slower than IPv4 but only by a fraction of a second, which is not noticeable to the human eye. Furthermore, the location of the user may also affect the response time.

Should you use IPv4 or IPv6?

You can use both IPv4 and IPv6, as most browsers will verify whether a website supports IPv6 and will send a request via IPv4 if it does not.

IPv6 and VPNs: Does IPv6 support matter for VPNs?

Many popular VPN providers, do not currently support IPv6. However, if you are using an IPv4 address, your VPN will work perfectly, and your data will be protected as it travels through the encrypted tunnel using the IPv4 protocol. Most VPN software currently operates on IPv4, and attempting to use IPv6 over an IPv4-only VPN will likely redirect your IPv6 traffic through the default gateway and ISP, which could compromise your security.

So what should you choose from IPv4 and IPv6?

In conclusion, the choice between IPv4 and IPv6 ultimately depends on your specific needs and circumstances. While IPv4 remains the dominant protocol, IPv6 offers several benefits, including improved security, end-to-end connectivity, and no geographical limitations. However, it is important to note that not all devices and networks are compatible with IPv6, and some major VPN providers do not support it yet. For most users, a combination of both IPv4 and IPv6 is the best solution, as browsers and devices can automatically switch between the two protocols as needed. As the internet continues to evolve and IPv6 adoption increases, it is important to stay informed and keep an eye on future developments in this area.

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shahek raza
shahek raza
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