1. Address Space: IPV4 has only 32-bit addressing scheme, providing a maximum of 4.3 billion IP addresses which were quickly exhausted.
1. Security: IPV4 lacked built-in security features and has been found to be vulnerable to a variety of security threats, including IP spoofing, DOS attacks, and IP fragmentation attacks.
1. Quality of Service: IPV4 had very limited support for Quality of Service (QoS), which made it more difficult to manage and prioritize network traffic.
1. Mobility: IPV4 was not designed with mobility in mind, and it could not handle seamless transitions between different networks or between wired and wireless connections.
1. Routing: IPV4 routing protocol has limitations, such as distance-vector routing, which can result in inefficient routing, slow convergence, and potential routing loops.
1. Scalability: IPV4 was not designed to scale to accommodate the rapidly growing number of internet users and devices as predicted in the future.
1. Multicast: Multicasting was not supported in IPV4 or only limited to inefficient techniques.
All these limitations led to the development of IPV6, which addresses these issues with a new 128-bit addressing scheme, built-in security features, better support for QoS, improved mobility, enhanced routing protocols, better scalability, and robust multicast capabilities.
