Which statement about EIGRP is true?

• A. It started as Cisco proprietary and later became an open standard
• B. It is pure distance-vector with no link-state features
• C. It uses UDP exclusively
• D. It is only used in IPv6 networks

Answer: (A)

EIGRP started as Cisco’s proprietary routing protocol and was later published as an open standard, which is why this statement is true. That history matters because it explains how EIGRP blends familiar routing ideas with Cisco’s innovations and why it has since been standardized for broader use. In practice, EIGRP is not just a simple distance-vector protocol; it uses an enhanced distance-vector approach with the DUAL algorithm to guarantee loop-free paths and fast convergence. It doesn’t rely on UDP for transport; updates travel using EIGRP’s own reliable transport mechanism at the IP layer. And it isn’t limited to IPv6—EIGRP supports both IPv4 and IPv6 networks.