Make sure to wrap domain names in quotes

dhcpd/files/dhcpd.conf

@@ -9,7 +9,7 @@ option domain-name "{{ salt['pillar.get']('dhcpd:domain_name') }}";
 {% endif -%}
 {% if salt['pillar.get']('dhcpd:domain_search', False) -%}
 option domain-search
-  {%- for dns_server in salt['pillar.get']('dhcpd:domain_search') %} {{ dns_server }}
+  {%- for search_domain in salt['pillar.get']('dhcpd:domain_search') %} "{{ search_domain }}"
     {%- if not loop.last %}, {% else %};{% endif %}
   {%- endfor %}
 {% endif -%}