Why does IPV6 use separate extension headers? Explain.
The extension headers in Ipv6 are utilized for economy and extensibility. Partitioning the datagram functionality in separation headers is economical since this saves space. Also containing separate headers in Ipv6 creates this possible to describe large set of features without needing each datagram header to contain at least one field for all features.
Extensibility comes in existence while new features are needed to be added to a protocol. Protocol as Ipv4 requires complete change, the header should be redesigned to accommodate new features. However in Ipv6, existing protocol header keeps unchanged. A new header field can be explained to accommodate new change.