suggested changes that includes:

moving actions for custom domain in its own controller
use separate service class for custom domains
updated help text for custom domains
increased test coverage for custom domains

app/services/conference_domains_service.rb

@@ -0,0 +1,27 @@
+class ConferenceDomainsService
+  def initialize(params)
+    @conference = params[:conference]
+  end
+
+  ##
+  # Checks if domain correctly points to the hosted version
+  # This feature is enabled only if ENV['OSEM_HOSTNAME'] is present
+  #
+  # ====Returns
+  # * +true+ -> If the custom domain has a CNAME record for the hosted version
+  # * +false+ -> If the custom domain does not have a CNAME record for the hosted version
+  def check_custom_domain
+    require 'resolv'
+
+    unless ENV['OSEM_HOSTNAME'].nil?
+      cname_record = Resolv::DNS.new.getresources(@conference.custom_domain, Resolv::DNS::Resource::IN::CNAME)
+      if cname_record.present?
+        return ENV['OSEM_HOSTNAME'] == Resolv::DNS.new.getresources(custom_domain, Resolv::DNS::Resource::IN::CNAME).first.name.to_s
+      else
+        return false
+      end
+    end
+
+    '--feature disabled--'
+  end
+end