Front view of a space grey color iPhones 6, 5s, 4 and 3gs generation showing the home screens on wooden background

IPv4 vs IPv6: What’s the Difference?

Not all IP (short for “internet protocol”) addresses are created equal. IP establishes common rules for information-packet exchange that allow computer networks to function cohesively. For each device to be able to communicate with other devices over the internet, they must be uniquely identified. IP works in tandem with the Transmission Control Protocol (TCP) to make sure everything connected to the internet knows how and where to send traffic. IPv4 was the fourth and most common IP system today, while many are making efforts to make the sixth system, IPv6, the more preferred system today.

We’ll explore the key differences site hosts must be aware of when considering IPv4 vs IPv6 addresses and how each internet protocol version is right for their purposes.

What is IPv4?

IPv4 is the original internet protocol addressing system, first applied by the early internet’s ARPANET system in 1983. Over 90% of internet traffic still uses an IPv4 address because it is extremely versatile and is easily accommodated by the general infrastructure of the internet to this day.

With IPv4’s 32-bit address format, more than 4 billion unique IP address combinations are possible—2^32, to be precise. Still, the proliferation of the internet and computing capabilities led computer scientists to develop an IP address format with much higher bit rates. Though IPv4 has certain limitations, it still has certain features that the IPv6 format does not, which could extend the IPv4 system’s use even as transitions to IPv6 take place. For how long that would be the case, nobody can be sure, but it is certain that IPv4 will not simply become obsolete out of the blue.

What is IPv6?

With 128 bits, this IP version provides the capacity for 340 undecillion unique IP address combinations—effectively, an infinite amount. Also called “IPng” (or “Internet Protocol next generation”), IPv6 was invented by the Internet Engineering Task Force in 1994 and deployed in 1998 mainly in order to provide more IP addresses but also to resolve certain limitations inherent to IPv4. This includes overcoming limitations to allowing multiple access devices to connect to the internet at once.

Key Differences

While IPv6 was invented to improve on certain limitations of IPv4, there are still unique differences between the two which make it hard to say that one is outright better than the other. They both accomplish the main task of identifying machines connected via a network, but they accomplish that task in very different ways with advantages and disadvantages of their own.

One major difference is that IPv6 has a hierarchical addressing and routing infrastructure, which simplifies routing tables for various links on a website and the devices linked to that website server’s network (or, more specifically, the unique identifiers of those devices). IPv4 requires many multiple identifiers that can become confusing, whereas IPv6 can use a single value with multiple prefixes to accomplish the same thing without complicated routing tables and algorithms.

Other key differences between IPv4 vs IPv6 addresses include the following:

  • IPv6 does not support IP address broadcasting, which IPv4 does by necessity.
  • IPv4 maps to MAC addresses via Address Resolution Protocol (ARP), while IPv6 utilizes Neighbor Discovery Protocol (NDP) to accomplish the same thing.
  • Due to its size limitations, IPv4 is separated into five distinct classes – IPv6 has no need for class categories.

IPv6 and IPv4 Nomenclature

You can spot the difference between the two address formats easily according to whether the address is numeric or alphanumeric. IPv4 uses strictly numeric IP addresses, while IPv6 makes use of alphanumeric hexadecimal characters. Also, the binary bits in IPv4 addresses are separated by a dot (.) – IPv6 addresses separate binary bits with a colon (:) instead. Here is an example of both:


IPv6: 3ffe:1900:fe20:4554:0000:0000:0000:0000

The larger bit length of IPv6 allows for greater simplification in data packet exchange and routing databases. This is not only easier for network managers to handle, it leads to greater efficiency too. Complicated subnet and header systems do not need to be relied on, and packet exchange can take place without as much computing needed to resolve packet exchange and routing algorithms.

Ensuring Compatibility Between IPv4 and IPv6

This is the way things are headed, but it should be noted that IPv4 still must be accommodated for, and for good reasons. For one, the vast majority of networking I.T. and infrastructure was created based on IPv4, and it needs to be maintained alongside IPv6. Another reason is that, however improved IPv6 is in many ways, IPv4 still has certain features that IPv6 does not have – see more in the pros and cons section below.

Improving IP Address Security

Yet when it comes to security and privacy, matters of increasing concern, it is clear that the advantages of IPv6 over IPv4 are more significant. Being newer, IPv6 has been built with the luxury of greater knowledge and hindsight. For instance, IPsec (IP Security) comes standard with IPv6, whereas it is only an option with IPv4 that may or may not be employed – it depends on whether or not the application utilizing IPv4 is designed to make use of IPsec.

Security is further enhanced through IPv6’s identity verification and data consistency. This has the added benefit of improving confidentiality and privacy, and those who make online privacy a priority would do well to use IPv6 instead of IPv4 whenever possible.

Pros and Cons of IPv4

While some of the pros and cons of each IP address system are merely differences, there are some clear advantages to each. Which is considered a pro or con, and to what extent, depends much on the network environment being used, but the following should serve as an outline of the qualities that make IPv4 and IPv6 unique.

Pros of IPv4

  • Supports VLSM (Variable Length Subnet Masking)
  • Simple virtual communication layers across diversified devices
  • Requires less memory than IPv6
  • Enables video conferences and libraries
  • More header fields (12) than IPv6 (8)
  • Has checksum fields
  • Utilizes broadcast address types
  • Widespread Network Address Translation (NAT) devices make end-to-end integrity possible via non-routable address masking.

Cons of IPv4

  • Less ideal than IPv6 for neighboring node interactions.
  • Much smaller bit-depth than IPv6.
  • System configuration is not optional.
  • Does not support auto-configuration and requires more maintenance.
  • Less inherently secure – security is dependent on applications.

Pros and Cons of IPv6

Pros of IPv6

  • Nearly infinite unique addresses are available, allowing for direct addressing.
  • Larger address space.
  • Hierarchal addressing and routing infrastructure, leading to simplified routing tables for websites.
  • Theoretically faster than IPv4 due to its non-reliance on NAT.
  • Supports multicast, a feature that allows high-bandwidth packet flows to be transmitted to several destinations at the same time.
  • More secure – built with IPsec (Internet Protocol Security) and compatible with proper key infrastructure.
  • Stateful and stateless configuration.
  • Quality of Service (QoS) support.
  • Longer header field (40) than IPv4 (20).
  • Utilizes anycast address types.
  • Better suited for mobile devices and mobile network applications.

Cons of IPv6

  • Does not support VLSM (Variable Length Subnet Masking).
  • Does not have checksum fields.
  • Only allows data packet fragmentation from hosts, not routers.

Which is Better?

Because IPv6 is the sixth and most recent internet protocol system, it has been built with greater security, speed, and efficiency. Certain of the IPv6 system’s qualities, such as its much longer bit length, are inherently useful, while others are simply greater capabilities that the network environment (and the internet in general) has yet to make full use of. Nevertheless, IPv6 must be transitioned to on account of the IPv4 address limitations alone, and it is important to make sure that one’s future networking efforts are oriented more towards IPv6.

At the same time, IPv4 is not going away, and so websites and networking equipment must still be backward compatible with IPv4 to ensure a maximum level of cohesion. The entire purpose of internet protocol addressing standards generally is, as it always was, to ensure that networking equipment can function together according to a universal system. Reconciling different systems to accomplish these ends is now a more important technical matter, but it is also not a problem.

In fact, IPv4 still has certain qualities that IPv6 doesn’t, making it useful for its novelty as well as the fact that the vast majority of networking equipment was built according to IPv4 standards. As IPv6 is more quickly transitioned to, it must accommodate all that IPv4 has built – to be essentially as backward compatible as possible – but it also is unlikely to completely replace it except possibly at some time in the far future.

We Manage Your Website While You Manage Your Business

WP Engine keeps even the steepest learning curves from eclipsing the day-to-day operations you rely on your website to support. With WordPress running so much of the worldwide web, our full-suite managed WordPress hosting services take the technicality off of your plate and enable you to focus on the creative works that make your site and your business valuable to your customers.

Our dedicated team of award-winning experts will update your existing site to IPv6 address compatibility or ensure that your new site is made fully compliant with the IPv6 transition underway. If your website handles any sum of money and sensitive customer data, it is imperative that you upgrade to the most secure systems available.

We are with you every step of the way and offer further indispensable services that can quickly save or even make you money. Our WordPress optimization services and redundancy drive the performance metrics that matter most while you focus on developing new products and providing attentive customer service. WP Engine also specializes in cutting-edge site security, site speed, and SEO tweaks that convert to greater sales. Learn more about what we can do for your website by clicking on the chat icon in the lower right, and tell us what your e-commerce goals are so we know better how to assist you.

Get started.

Build faster, protect your brand, and grow your business with a WordPress platform built to power remarkable online experiences.