IPv4 vs IPv6: Differences, Diagram, Features & Examples

Introduction

IPv4 and IPv6 are two versions of the Internet Protocol (IP), which carries packets between devices across networks. The most significant difference is the size of their addresses: IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses, providing a much larger address space. These differences also affect network configuration, packet handling and troubleshooting.

A website may be accessible over IPv4 but unavailable over IPv6, even when both protocols point to the same server. Understanding how IPv4 and IPv6 work helps network administrators identify connectivity problems and plan networks that support both protocols.

IPv4 vs IPv6: One Website, 2 Different Results

Let’s say you manage an inventory dashboard for a warehouse. You enable IPv6 on its server and add an IPv6 address to DNS then the IPv4 address will remain in the same place.

DNS records now look like this:

Record type	Dashboard hostname	Example address
A: IPv4 address	inventory.example.com	192.0.2.40
AAAA: IPv6 address	inventory.example.com	2001:db8:40::10

These addresses are reserved for documentation.

After the change, your office laptop opens the dashboard normally. But an IPv6 connection test from another network times out.

You test each protocol separately:

curl -4 -I https://inventory.example.com

curl -6 -I https://inventory.example.com

The first command returns an HTTP response, while the second cannot connect. In this hypothetical example, the server’s firewall allows HTTPS over IPv4 but has no matching IPv6 rule. Adding the appropriate IPv6 rule restores access.

A working IPv4 connection does not prove that IPv6 works. DNS records, routes, application listeners and firewall rules must be checked for each protocol.

Understanding how IPv4 and IPv6 work is essential for identifying and fixing network connectivity issues. If you want to build these practical networking skills, explore our CCNA Training, where you can learn IP addressing, routing, switching, and network troubleshooting through hands-on practice.

IPv4 vs IPv6 Diagram: Separate Paths to Same Service

IPv4 and IPv6 can provide access to the same website, but they use different addressing systems and network paths. A device may connect successfully over IPv4 while an IPv6 connection fails because of issues with DNS records, routing or firewall rules. The diagram below illustrates how both protocols reach the same service and where connectivity problems can occur.

Difference Between IPv4 and IPv6

IPv4 and IPv6 differ in address format, size, configuration, and network communication. In the sections below, we’ll explain each protocol in detail, compare their key features, and explore their practical differences in networking.

What Is IPv4?

IPv4 stands for Internet Protocol version 4, it carries packets containing source and destination addresses, allowing routers to forward traffic toward its destination.

An IPv4 address looks like this:

192.168.10.25

It contains four decimal numbers separated by dots. Each number represents eight bits and ranges from 0 to 255. Together, they form a 32-bit address. That gives IPv4 approximately 4.3 billion possible addresses, although reserved ranges mean they are not all available for public devices.

That is why IPv4 provides best-effort delivery. It does not independently guarantee that packets arrive, remain in order, or get retransmitted after loss. Protocols such as TCP handle those tasks when required.

Key Features of IPv4

IPv4 remains widely used because it is simple to configure and supported by most networking devices and systems. Its key features include a familiar address format, flexible configuration methods and NAT for sharing public IP addresses.

1. Familiar Address Format: Short decimal addresses are relatively easy to read.

1. Manual or Automatic Configuration: Administrators can assign addresses manually or use DHCP.

1. Public and Private Addressing: Private addresses support internal networks.

1. Address Sharing: NAT commonly allows multiple private devices to share a public IPv4 address.

What Is IPv6?

IPv6 stands for Internet Protocol version 6. It expands the address size to 128 bits, providing approximately 3.4 × 10³⁸ possible addresses.

An IPv6 address can look like this:

2001:0db8:0040:0000:0000:0000:0000:0010

IPv6 uses hexadecimal digits—numbers 0–9 and letters a–f—arranged in eight colon-separated groups. 

You can remove leading zeros within groups and replace a consecutive sequence of all-zero groups with ::. The same address becomes:

2001:db8:40::10

The :: abbreviation can appear only once in an address; otherwise, the number of omitted groups would be ambiguous.

Key Features of IPv6

IPv6 was developed to address the limitations of IPv4, particularly the shortage of available IP addresses. It offers a much larger address space, simplified packet headers and automatic configuration features that support modern networks.

1. Much Larger Address Space: Networks can allocate addresses without the same scarcity constraints.

1. Automatic Configuration: SLAAC allows devices to generate addresses using information advertised by routers.

1. No Broadcast Addressing: IPv6 uses multicast for functions that require communication with selected groups.

1. Fixed Base Header: Its main header has a consistent structure, with extension headers carrying additional information when needed.

IPv4 vs IPv6 Comparison Table

This IPv4 vs IPv6 comparison covers the differences you are most likely to encounter when configuring or troubleshooting a network.

Feature	IPv4	IPv6
Address length	32 bits	128 bits
Address format	Decimal numbers separated by dots	Hexadecimal groups separated by colons
Example	192.0.2.40	2001:db8:40::10
Possible addresses	About 4.3 billion	About 3.4 × 10³⁸
IP header size	20–60 bytes	40-byte base header, plus extensions if present
Header checksum	Included	Not included
Typical address configuration	Manual or DHCP	Manual, SLAAC, or DHCPv6
Broadcast	Supported	Not used
Local address resolution	ARP	Neighbor Discovery using ICMPv6
Fragmentation	Sender or routers, when permitted	Source only
DNS address record	A	AAAA
Loopback address	Commonly 127.0.0.1	::1

What Is the Difference Between IPv4 and IPv6 in Practice?

IPv4 and IPv6 differ in more than just address length; they also affect how devices connect, discover routers and handle network traffic. Understanding these practical differences helps network administrators configure networks correctly, troubleshoot connectivity issues and secure both protocols.

1. Address Availability and NAT

Imagine an office that has 80 laptops with private IPv4 addresses. Its router can use Network Address Translation usually with port translation, to let those devices share one public IPv4 address. The router tracks outgoing connections and directs replies to the correct laptop.

IPv6 provides enough address space for devices to use individual globally routable addresses without sharing one address merely to conserve supply. A globally routable address doesn’t mean unrestricted access. Firewall rules still determine which connections are allowed.

2. Address Configuration and Router Discovery

IPv4 networks commonly use DHCP to supply an address and other settings. IPv6 introduces Stateless Address Autoconfiguration, or SLAAC. A router advertises a network prefix, and a device can use that information to form an address. DHCPv6 is another option for supplying addresses or configuration details, depending on the network design.

One distinction matters during troubleshooting: IPv6 hosts normally discover their default routers through Router Advertisements, rather than receiving a default gateway through DHCPv6. A device can therefore have an IPv6 address while still lacking a usable route beyond its local network.

3. Local Network Communication

Before sending a packet over Ethernet, a device needs the link-layer address of its next hop. IPv4 commonly uses Address Resolution Protocol, or ARP, for this lookup. IPv6 uses Neighbour Discovery Protocol, or NDP, through ICMPv6 messages.

NDP also helps devices discover routers and determine whether neighbours remain reachable. This means blocking all ICMPv6 traffic can break essential network functions. Treating it as nothing more than “ping traffic” is a configuration mistake.

4. Packet Headers and Fragmentation

An IPv4 header can vary in length. IPv6 uses a fixed 40-byte base header. Be careful with the claim that IPv6 has a “smaller header.” Its base header is larger than IPv4’s minimum 20-byte header, although its structure is simpler.

Fragmentation also changes. IPv4 routers can fragment packets when permitted. IPv6 routers do not; if a packet exceeds the next link’s maximum transmission unit, the router drops it and sends an ICMPv6 Packet Too Big message. The sender must then adjust packet sizing or use source fragmentation as appropriate.

IPv6 vs IPv4: Which Is Faster?

IPv6 is not automatically faster than IPv4. The actual speed depends on factors such as network congestion, routing efficiency, internet service provider connectivity and server configuration. In some cases, IPv6 may provide a more direct route to a destination, while in others, IPv4 may perform better. 

To compare IPv4 and IPv6 accurately, test both protocols against the same website or application under similar network conditions. Check connection time, latency, packet loss and download speed to understand the differences. A properly configured IPv6 connection can perform as well as or better than IPv4, but the results depend on the network and the route taken.

Is IPv6 More Secure Than IPv4?

IPv6 does not automatically encrypt your traffic. Both the IPv4 and IPv6 can use IPsec. Having protocol support available is different from configuring and using it. HTTPS also remains necessary for protecting web traffic, regardless of the IP version underneath it.

For administrators, the practical requirement is consistent protection across both protocols:

1. Apply equivalent access policies to IPv4 and IPv6.

1. Check which addresses applications listen on.

1. Include IPv6 traffic in logging and monitoring.

1. Permit the ICMPv6 messages needed for network operation.

Enabling IPv6 while overlooking its security rules creates an unmanaged path into the environment.

Can IPv4 and IPv6 Work Together?

Yes, IPv4 and IPv6 work together but they use different packet formats. An IPv4-only endpoint cannot directly exchange native IPv6 packets with an IPv6-only endpoint.

Two established transition approaches are:

Approach	How it works
Dual stack	Devices run both protocols and use the appropriate one for a connection.
Tunnelling	IPv6 packets travel inside IPv4 packets across an IPv4 network between tunnel endpoints.

Dual stack lets a service maintain IPv4 access while adding IPv6. However, it also means operating and testing two sets of network behaviour. Tunnelling carries IPv6 across an intervening network; it does not make an IPv4-only application understand IPv6.

Conclusion

IPv4 and IPv6 differ in address capacity, configuration, packet handling and network communication. While IPv4 remains widely used, IPv6 provides a much larger address space and supports modern network requirements. Understanding both protocols helps administrators troubleshoot connectivity, configure routing and apply consistent security policies. Testing IPv4 and IPv6 independently ensures reliable connectivity and helps identify protocol-specific network issues.

Frequently Asked Questions

Q1. What is the Main Difference Between IPv4 and IPv6?

Ans: The IPv4 uses the 32-bit address while the IPv6 uses the 128-bit address, The IPv6 provides a significantly more addresses and it changes how devices are configured with connections. 

Q2. Is IPv6 Faster Than IPv4?

Ans: No, the IPv6 does not make the internet faster for you. The performance of the network depends on routing and congestion along with the provider connectivity and server configuration. Test both the internet protocols against the same service to compare the actual performance. 

Q3. Can a Device Use IPv4 and IPv6 Together?

Ans: Yes, the devices can run IPv4 and IPv6 together using the same dual stack. Each of the connections uses one protocol. For both protocols administration should always check of DNS, routing, firewall rules and the application support.

Q4. Does IPv6 Automatically Provide Better Security?

Ans. No, the IPv6 does not encrypt the traffic on its own. Both of the protocols can use the IPSec and HTTPS which protects the web traffic over the either version. Security depends on the correct configuration and access control.