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.
Kind regards,
Buck
_______________________________________________
Dnsmasq-discuss mailing list
Dnsmasq-discuss@lists.thekelleys.org.uk
https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss
