---
title: "Why doesn't 'dhclient -6' work?"
slug: "aa-01212"
description: "DHCPv6 clients use their IPv6 link-local addresses to communicate with the server. If IPv6 is not enabled on the interface, communication is not possible."
tags: ["isc dhcp"]
updated: 2018-10-30T19:07:19Z
published: 2018-10-30T19:07:19Z
canonical: "kb.isc.org/aa-01212"
---

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# Why does "dhclient -6" not work if I haven't already enabled IPv6 on the interface?

IPv6 makes extensive use of the "link-local" address. This address is configured automatically when the interface is brought up. Various IPv6 subprotocols, including Neighbor Discovery Protocol (NDP) and DHCPv6, require and use this address.

The IPv6 link-local address is in the FE80::/64 space (which is within the reserved FE80::/10 network). Every IPv6-enabled interface will have this address at a minimum. Link-local means just that: it is local to the link (interface or Ethernet segment) only, and it cannot be routed outside that link.

Your operating system (OS) will statelessly autoconfigure the IPv6 link-local address when IPv6 is enabled on the interface. The details of how this is done vary per OS, but the governing standard is [RFC 4862](https://tools.ietf.org/html/rfc4862), IPv6 Stateless Address Autoconfiguration.

DHCPv6 clients use their IPv6 link-local addresses to communicate with the server.[1] If you have not enabled IPv6 on the interface, there is no link-local address yet, and the client is unable to reach the server.

[1] See [section 1.1](https://tools.ietf.org/html/rfc3315#section-1.1) of RFC 3315.

References: [RFC 3315](https://tools.ietf.org/html/rfc3315), Dynamic Host Configuration Protocol for IPv6 (DHCPv6) [RFC 4291](https://tools.ietf.org/html/rfc4291), IP Version 6 Addressing Architecture (see [section 2.5.6](https://tools.ietf.org/html/rfc4291#section-2.5.6)) [RFC 4862](https://tools.ietf.org/html/rfc4862), IPv6 Stateless Address Autoconfiguration