> Hi Yeoh, > > On 28.07.24 23:42, Yeoh via Dnsmasq-discuss wrote: >> Does 'option:42' or 'option:ntp-server' support using IPv6 addresses or a >> domain name ? >> >> I mean instead of using an IP literal address we can instead specify a >> domain name that resolves to multiple IP's (IPv4/IPv6). > > > DHCP is strictly IPv4, and RFC 2132 defines option 42 as 'a list of IP > addresses'. > This would neither allow domains nor IPv6 addresses. > > For IPv6, DHCPv6 is the equivalent protocol. > > RFC 5908 allows to state an IPv6 address as well as a FQDN as a > suboption of option code 56, where the NTP servers conveyed in either > way should be part of the organisation that configures them (in an > effort to reduce load on public NTP servers). > > dnsmasq supports IPv6 addresses notated as > dhcp-option=option6:ntp-server,[1234::56]. > I am unaware whether FQDNs would be allowed as well. The documentation > mentioning only IPv6 addresses seems to suggest they are currently not. > > However, note that IPv6 clients commonly would prefer SLAAC over > stateful or stateless DHCPv6 to configure their network stack. There are > even OSs that do not support DHCPv6 at all, Android being the prime > example here. > > With NDP/SLAAC, clients should pick up network information from Router > Advertisements as broadcasted by a router. > I am not aware of an RFC defining router advertisements conveying NTP > server information. > > Thus, using DHCP with IPv4 addresses would seem the most reliable way to > convey NTP server information to IPv4 as well as dual stack clients. >
Hi Buck, Thanks for the hint. DHCPv6 option6 for ntp-server does indeed take an FQDN too. Regards, Yeoh _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss
