[Kea-users] Kea DHCP - next-server Field Does Not Accept FQDN

[Dipesh Kayastha]

Hi Darren,

Thank you for confirming the behavior.

I’ve opened an issue to track this limitation:
👉 https://gitlab.isc.org/isc-projects/kea/-/issues/3951

I hope this can be addressed as soon as possible, as it’s currently
blocking smooth migration from ISC DHCP in DNS-based environments.

Best regards,
Dipesh


>
> Hi Dipesh,
>
> This is not currently supported. You can open an issue here:
> https://gitlab.isc.org/isc-projects/kea/-/issues/ requesting the support
> be
> added.
>
> Thank you,
> Darren Ankney
>
> On Fri, Jun 13, 2025 at 2:13?AM Dipesh Kayastha <
> er.dipesh.kayastha at gmail.com> wrote:
>
> > Dear Kea Development Team,
> >
> > I am currently working on migrating configurations from ISC DHCP (dhcpd)
> > to Kea DHCP and encountered a limitation regarding the next-server field.
> >
> > In ISC DHCP, it is valid to specify either an IP address or a fully
> > qualified domain name (FQDN) for the next-server directive, as referenced
> > in the dhcpd.conf man page:
> > https://linux.die.net/man/5/dhcpd.conf
> >
> > However, in Kea, the next-server field under subnet4 appears to accept
> > only IPv4 addresses. If an FQDN is used (e.g., "next-server": "
> > pxe.boot.example.com"), the configuration fails to parse and returns an
> > error like:
> >
> >
> > *2025-06-12 13:35:40.228 ERROR [kea-dhcp4.dhcp4/1.140187402663808]
> > DHCP4_CONFIG_LOAD_FAIL configuration error using **file:
> > /etc/config/kea4.conf**, reason: subnet configuration failed: invalid
> > parameter next-server : *pxe.boot.example.com
> *(/etc/config/kea4.conf:169:24)
> > *
> >
> > This becomes a compatibility issue during migration, especially in
> > environments that rely on DNS to resolve boot server IPs dynamically.
> >
> > However, ISC DHCP (dhcpd) supports both IP addresses and FQDNs in the
> > next-server field, as documented here:
> >
> > https://linux.die.net/man/5/dhcpd.conf
> > [image: image.png]
> >
> >
> > Is there any plan to support FQDNs in Kea for the next-server field,
> > similar to how ISC DHCP handles it? FQDN support can be useful in dynamic
> > environments where the boot server?s IP address may change and is managed
> > via DNS.
> >
> > I'm looking forward to hearing back from you
> >
> >
> > Regards,
> > .Dipesh
> >
> > --
>

On Fri, Jun 13, 2025 at 11:43 AM Dipesh Kayastha <
er.dipesh.kayastha at gmail.com> wrote:

> Dear Kea Development Team,
>
> I am currently working on migrating configurations from ISC DHCP (dhcpd)
> to Kea DHCP and encountered a limitation regarding the next-server field.
>
> In ISC DHCP, it is valid to specify either an IP address or a fully
> qualified domain name (FQDN) for the next-server directive, as referenced
> in the dhcpd.conf man page:
> https://linux.die.net/man/5/dhcpd.conf
>
> However, in Kea, the next-server field under subnet4 appears to accept
> only IPv4 addresses. If an FQDN is used (e.g., "next-server": "
> pxe.boot.example.com"), the configuration fails to parse and returns an
> error like:
>
>
> *2025-06-12 13:35:40.228 ERROR [kea-dhcp4.dhcp4/1.140187402663808]
> DHCP4_CONFIG_LOAD_FAIL configuration error using **file:
> /etc/config/kea4.conf**, reason: subnet configuration failed: invalid
> parameter next-server : *pxe.boot.example.com*(/etc/config/kea4.conf:169:24)
> *
>
> This becomes a compatibility issue during migration, especially in
> environments that rely on DNS to resolve boot server IPs dynamically.
>
> However, ISC DHCP (dhcpd) supports both IP addresses and FQDNs in the
> next-server field, as documented here:
>
> https://linux.die.net/man/5/dhcpd.conf
> [image: image.png]
>
>
> Is there any plan to support FQDNs in Kea for the next-server field,
> similar to how ISC DHCP handles it? FQDN support can be useful in dynamic
> environments where the boot server’s IP address may change and is managed
> via DNS.
>
> I'm looking forward to hearing back from you
>
>
> Regards,
> .Dipesh
>
>
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