diff --git a/app/models/nameserver.rb b/app/models/nameserver.rb
index 729ac6cbf..00a06c95f 100644
--- a/app/models/nameserver.rb
+++ b/app/models/nameserver.rb
@@ -16,6 +16,7 @@ class Nameserver < ActiveRecord::Base
   # rubocop: enable Metrics/LineLength
 
   before_validation :normalize_attributes
+  before_validation :check_puny_symbols
   
   delegate :name, to: :domain, prefix: true
 
@@ -41,6 +42,11 @@ class Nameserver < ActiveRecord::Base
     self.ipv6 = Array(ipv6).reject(&:blank?).map(&:strip).map(&:upcase)
   end
 
+  def check_puny_symbols
+    regexp = /(\A|\.)..--/
+    errors.add(:hostname, :invalid) if hostname =~ regexp
+  end
+
   def to_s
     hostname
   end