<div dir="ltr"><div dir="ltr"><div dir="ltr"><p>Hi Darren,</p><p>Thank you for confirming the behavior.</p><p>I’ve opened an issue to track this limitation:<br>👉 <a rel="noopener" href="https://gitlab.isc.org/isc-projects/kea/-/issues/3951" target="_blank">https://gitlab.isc.org/isc-projects/kea/-/issues/3951</a></p><p>I hope this can be addressed as soon as possible, as it’s currently blocking smooth migration from ISC DHCP in DNS-based environments.</p><p>Best regards,<br>Dipesh</p></div><div class="gmail-yj6qo gmail-ajU" style="outline:none;padding:10px 0px;width:22px;margin:2px 0px 0px"><div id="gmail-:137" class="gmail-ajR" role="button" tabindex="0" aria-label="Hide expanded content" aria-expanded="true" style="background-color:rgb(232,234,237);border:none;clear:both;line-height:6px;outline:none;width:24px;border-radius:5.5px"><img class="gmail-ajT" src="https://ssl.gstatic.com/ui/v1/icons/mail/images/cleardot.gif" style="background: url("https://www.gstatic.com/images/icons/material/system_gm/2x/more_horiz_black_20dp.png") 50% 50% / 20px no-repeat; height: 11px; opacity: 0.71; width: 24px;"></div></div><div class="gmail-adL"><div class="gmail-adm" style="margin:5px 0px"></div><div class="gmail-im" style="color:rgb(80,0,80)"><br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br><br>Hi Dipesh,<br><br>This is not currently supported. You can open an issue here:<br><a href="https://gitlab.isc.org/isc-projects/kea/-/issues/" rel="noreferrer" target="_blank">https://gitlab.isc.org/isc-projects/kea/-/issues/</a> requesting the support be<br>added.<br><br>Thank you,<br>Darren Ankney<br><br>On Fri, Jun 13, 2025 at 2:13?AM Dipesh Kayastha <<br><a href="mailto:er.dipesh.kayastha@gmail.com" target="_blank">er.dipesh.kayastha@gmail.com</a>> wrote:<br><br>> Dear Kea Development Team,<br>><br>> I am currently working on migrating configurations from ISC DHCP (dhcpd)<br>> to Kea DHCP and encountered a limitation regarding the next-server field.<br>><br>> In ISC DHCP, it is valid to specify either an IP address or a fully<br>> qualified domain name (FQDN) for the next-server directive, as referenced<br>> in the dhcpd.conf man page:<br>> <a href="https://linux.die.net/man/5/dhcpd.conf" rel="noreferrer" target="_blank">https://linux.die.net/man/5/dhcpd.conf</a><br>><br>> However, in Kea, the next-server field under subnet4 appears to accept<br>> only IPv4 addresses. If an FQDN is used (e.g., "next-server": "<br>> <a href="http://pxe.boot.example.com/" rel="noreferrer" target="_blank">pxe.boot.example.com</a>"), the configuration fails to parse and returns an<br>> error like:<br>><br>><br>> *2025-06-12 13:35:40.228 ERROR [kea-dhcp4.dhcp4/1.140187402663808]<br>> DHCP4_CONFIG_LOAD_FAIL configuration error using **file:<br>> /etc/config/kea4.conf**, reason: subnet configuration failed: invalid<br>> parameter next-server : *<a href="http://pxe.boot.example.com/" rel="noreferrer" target="_blank">pxe.boot.example.com</a>*(/etc/config/kea4.conf:169:24)<br>> *<br>><br>> This becomes a compatibility issue during migration, especially in<br>> environments that rely on DNS to resolve boot server IPs dynamically.<br>><br>> However, ISC DHCP (dhcpd) supports both IP addresses and FQDNs in the<br>> next-server field, as documented here:<br>><br>> <a href="https://linux.die.net/man/5/dhcpd.conf" rel="noreferrer" target="_blank">https://linux.die.net/man/5/dhcpd.conf</a><br>> [image: image.png]<br>><br>><br>> Is there any plan to support FQDNs in Kea for the next-server field,<br>> similar to how ISC DHCP handles it? FQDN support can be useful in dynamic<br>> environments where the boot server?s IP address may change and is managed<br>> via DNS.<br>><br>> I'm looking forward to hearing back from you<br>><br>><br>> Regards,<br>> .Dipesh<br>><br>> --<br></blockquote></div></div></div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Fri, Jun 13, 2025 at 11:43 AM Dipesh Kayastha <<a href="mailto:er.dipesh.kayastha@gmail.com">er.dipesh.kayastha@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><p>Dear Kea Development Team,</p><p>I am currently working on migrating configurations from ISC DHCP (dhcpd) to Kea DHCP and encountered a limitation regarding the <code>next-server</code> field.</p><p>In ISC DHCP, it is valid to specify either an IP address or a fully qualified domain name (FQDN) for the <code>next-server</code> directive, as referenced in the dhcpd.conf man page:<br>
<a rel="noopener" href="https://linux.die.net/man/5/dhcpd.conf" target="_blank">https://linux.die.net/man/5/dhcpd.conf</a></p><p>However, in Kea, the <code>next-server</code> field under <code>subnet4</code> appears to accept only IPv4 addresses. If an FQDN is used (e.g., <code>"next-server": "<a href="http://pxe.boot.example.com" target="_blank">pxe.boot.example.com</a>"</code>), the configuration fails to parse and returns an error like:</p><pre><div><div dir="ltr"></div></div></pre><p><br><strong style="color:rgb(23,43,77);font-family:-apple-system,"system-ui","Segoe UI",Roboto,Oxygen,Ubuntu,"Fira Sans","Droid Sans","Helvetica Neue",sans-serif;font-size:14px;letter-spacing:-0.07px">2025-06-12 13:35:40.228 ERROR [kea-dhcp4.dhcp4/1.140187402663808] DHCP4_CONFIG_LOAD_FAIL configuration error using </strong><span style="color:rgb(23,43,77);font-family:-apple-system,"system-ui","Segoe UI",Roboto,Oxygen,Ubuntu,"Fira Sans","Droid Sans","Helvetica Neue",sans-serif;font-size:14px;letter-spacing:-0.07px"><strong>file: /etc/config/kea4.conf</strong></span><strong style="color:rgb(23,43,77);font-family:-apple-system,"system-ui","Segoe UI",Roboto,Oxygen,Ubuntu,"Fira Sans","Droid Sans","Helvetica Neue",sans-serif;font-size:14px;letter-spacing:-0.07px">, reason: subnet configuration failed: invalid parameter next-server : </strong><span style="font-family:monospace"><a href="http://pxe.boot.example.com" target="_blank">pxe.boot.example.com</a></span><strong style="color:rgb(23,43,77);font-family:-apple-system,"system-ui","Segoe UI",Roboto,Oxygen,Ubuntu,"Fira Sans","Droid Sans","Helvetica Neue",sans-serif;font-size:14px;letter-spacing:-0.07px">(/etc/config/kea4.conf:169:24)
</strong></p><p>This becomes a compatibility issue during migration, especially in environments that rely on DNS to resolve boot server IPs dynamically.</p><p>However, ISC DHCP (dhcpd) supports both IP addresses and FQDNs in the <code>next-server</code> field, as documented here:<strong style="color:rgb(23,43,77);font-family:-apple-system,"system-ui","Segoe UI",Roboto,Oxygen,Ubuntu,"Fira Sans","Droid Sans","Helvetica Neue",sans-serif;font-size:14px;letter-spacing:-0.07px">
</strong></p><p>
<a rel="noopener" href="https://linux.die.net/man/5/dhcpd.conf" target="_blank">https://linux.die.net/man/5/dhcpd.conf</a><br></p><img src="cid:ii_mbueqsej0" alt="image.png" width="542" height="82"><p><br></p><p>Is there any plan to support FQDNs in Kea for the <code>next-server</code> 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.</p><p>I'm looking forward to hearing back from you<br><br><br>Regards,<br>.Dipesh</p><p>
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