diff --git a/app/models/record.rb b/app/models/record.rb
index d73f2c5..a3186fa 100644
--- a/app/models/record.rb
+++ b/app/models/record.rb
@@ -1,333 +1,341 @@
 require 'ipaddr'
 require_dependency 'drop_privileges_validator'
 
 class Record < ActiveRecord::Base
   belongs_to :domain
   # Powerdns inserts empty records on slave zones,
   # we want to hide them
   #
   # http://mailman.powerdns.com/pipermail/pdns-users/2013-December/010389.html
   default_scope { where.not(type: nil) }
 
   # List all supported DNS RR types.
   def self.record_types
     [
       'A', 'AAAA', 'CNAME',
       'MX',
       'TXT', 'SPF', 'SRV', 'SSHFP',
       'SOA', 'NS',
       'PTR', 'NAPTR',
       'DS'
     ]
   end
 
   # List types usually used in forward zones.
   def self.forward_records
     record_types - ['SOA', 'PTR']
   end
 
   # List types usually used in reverse zones.
   def self.reverse_records
     ['PTR', 'CNAME', 'TXT', 'NS', 'NAPTR', 'DS']
   end
 
   # List types usually used in enum zones.
   def self.enum_records
     ['NAPTR', 'CNAME', 'TXT', 'NS', 'DS']
   end
 
   # List types that can be touched by a simple user.
   def self.allowed_record_types
     record_types - WebDNS.settings[:prohibit_records_types]
   end
 
   validates :name, presence: true
   validates :type, inclusion: { in: record_types }
 
   # http://mark.lindsey.name/2009/03/never-use-dns-ttl-of-zero-0.html
   validates_numericality_of :ttl,
                             allow_nil: true, # Default pdns TTL
                             only_integer: true,
                             greater_than: 0,
                             less_than_or_equal_to: 2_147_483_647
 
   # Don't allow the following actions on drop privileges mode
   validate :no_touching_for_slave_zones, if: -> { domain.slave? }
 
   validates_drop_privileges :type,
                             message: 'You cannot touch that record!',
                             unless: -> { Record.allowed_record_types.include?(type) }
   validates_drop_privileges :name,
                             message: 'You cannot touch top level NS records!',
                             if: -> { type == 'NS' && domain_record? }
 
   validates_uniqueness_of :name,
                           :scope => [:domain, :type, :content],
                           message: "There already exists a record with the same name,
                             type and content."
 
   before_validation :guess_reverse_name
   before_validation :set_name
   after_save :update_zone_serial
   after_destroy :update_zone_serial
 
+  before_create :validate_unique_cname
   before_create :generate_classless_delegations, unless: -> { domain.slave? }
   before_destroy :delete_classless_delegations, unless: -> { domain.slave? }
 
   # Smart sort a list of records.
   #
   # Order by:
   # * Top level records
   # * Record name
   # * SOA
   # * NS
   # * Friendly type
   # * Priority
   # * Content
   #
   # records - The list of records to order.
   #
   # Returns the list sorted.
   def self.smart_order(records)
     records.sort_by { |r|
       [
         r.domain_record? ? 0 : 1,   # Zone records
         r.classless_delegated? ? 1 : 0,
         r.name,
         r.type == 'SOA' ? 0 : 1,
         r.type == 'NS' ? 0 : 1,
         record_types.index(r.type), # Friendly type
         r.prio || 0,
         r.content
       ]
     }
   end
 
   def self.search(query)
     wild_search = "%#{query}%" # !index_friendly
 
     where('name like :q or content like :q', q: wild_search)
   end
 
   # Get the a short name for the record (without the zone suffix).
   #
   # Returns a string.
   def short
     return '' if name == domain.name
     return '' if name.blank?
 
     File.basename(name, ".#{domain.name}")
   end
 
   # Returns true if this is a zone record.
   def domain_record?
     name.blank? || name == domain.name
   end
 
   # Find out if the record is edittable.
   #
   # by - Editable by :user or :admin.
   #
   # Returns true if the record is editable.
   def editable?(by = :user)
     return false if domain.slave?
     return false if classless_delegated?
 
     case by
     when :user
       return false unless Record.allowed_record_types.include?(type)
       return false if type == 'NS' && domain_record?
     end
 
     true
   end
 
   # Find out this record type supports priorities.
   #
   # We set this to false by default, record types that support priorities.
   # shoule override this.
   #
   # Returns true this record type support priorities.
   def supports_prio?
     false
   end
 
   # Make sure rails generates record specific urls for all record types.
   #
   # Overrides default rails STI behavior.
   def self.model_name
     return super if self == Record
 
     Record.model_name
   end
 
   # Generate the usual admin friendly DNS record line.
   #
   # Returns a string.
   def to_dns
     [name, ttl, 'IN', type, supports_prio? ? prio : nil, content].compact.join(' ')
   end
 
   # Generate a shorter version of the DNS record line.
   #
   # Returns a string.
   def to_short_dns
     [name, 'IN', type].join(' ')
   end
 
   def to_api
     Hash[
       :name, name,
       :content, content,
       :type, type,
       :ttl, ttl,
       :prio, prio,
       :disabled, disabled
     ].with_indifferent_access
   end
 
   def classless_delegated?
     return false if not type == 'CNAME'
     return false if not domain.name.end_with?('.in-addr.arpa')
 
     network, mask = parse_delegation(content)
     return false if network.nil?
 
     octet = name.split('.').first.to_i
     return true if octet >= network
     return true if octet <= network + 2 ^ (32 - mask) - 1 # max
 
     false
   end
 
   def classless_delegation?
     return true if classless_delegation
 
     false
   end
 
   def as_bulky_json
     Hash[
       id: id,
       name: name,
       type: type,
       ttl: ttl,
       prio: prio,
       content: content,
       disabled: disabled
     ]
   end
   private
 
   # Validations
 
   def no_touching_for_slave_zones
     # Allow automatic SOA creation for slave zones
     # powerdns needs a valid serial to compare it with master
     return if type == 'SOA' && validation_context == :create
 
     errors.add(:type, 'This is a slave zone!')
   end
 
   # Hooks
 
   def guess_reverse_name
     return if not type == 'PTR'
     return if not domain.reverse?
     return if name.blank?
 
     reverse = IPAddr.new(name).reverse
     self.name = reverse if reverse.end_with?(domain.name)
   rescue IPAddr::InvalidAddressError # rubycop:disable HandleExceptions
   end
 
   # Powerdns expects full domain names
   def set_name
     self.name = domain.name if name.blank?
     self.name = "#{name}.#{domain.name}" if not name.end_with?(domain.name)
   end
 
   def remove_terminating_dot
     self.content = content.gsub(/\.+\Z/, '')
   end
 
   def update_zone_serial
     # SOA records handle serial themselves
     return true if type == 'SOA'
     return true if !domain
 
     domain.soa.bump_serial!
   end
 
   def classless_delegation
     return if not type == 'NS'
     return if not domain.name.end_with?('.in-addr.arpa')
 
     network, mask = parse_delegation(name)
     return if network.nil?
 
     range = IPAddr.new("0.0.0.#{network}/#{mask}").to_range
     return if !range.first.to_s.end_with?(".#{network}")
 
     range.map { |ip|
       octet = ip.to_s.split('.').last
       "#{octet}.#{domain.name}"
     }
   end
 
   def parse_delegation(value)
     first, _rest = value.split('.', 2)
     first.gsub!('-', '/')
     return if !first['/']
 
     network, mask = first.split('/', 2).map { |i| Integer(i).abs }
     return if [network, mask].join('/') != first
     return if mask <= 24
     return if mask > 31
     return if network > 255
 
     [network, mask]
   rescue ArgumentError # Not an integer
   end
 
   def delete_classless_delegations
     rnames = classless_delegation
     return unless rnames
 
     # Check if we have another NS for the same delegation
     return if domain.records.where(type: 'NS', name: name)
                .where.not(id: id).exists?
 
     # Delete all CNAMEs
     domain.records.where(name: rnames,
                          type: 'CNAME',
                          content: name).delete_all
   end
 
   def generate_classless_delegations
     rnames = classless_delegation
     return unless rnames
 
     # Make sure no record exists for a delegated domain
     if domain.records.where(name: rnames)
         .where.not(content: name).exists?
 
       errors.add(:name, 'Records already exist for the delegated octets!')
       return false
     end
 
     rnames.each { |rname|
       CNAME.find_or_create_by!(
         domain: domain,
         name: rname,
         content: name
       )
     }
   end
 
   def self.to_fqdn(name, domain)
     return name if name.end_with?(domain)
 
     "#{name}.#{domain}"
   end
+
+  def validate_unique_cname
+    return if !domain.records.where(type: 'CNAME', name: name).exists?
+
+    errors.add(:name, 'There exists a CNAME record with the same name')
+    return false
+  end
 end
diff --git a/test/models/domain_test.rb b/test/models/domain_test.rb
index ef781a0..23dc784 100644
--- a/test/models/domain_test.rb
+++ b/test/models/domain_test.rb
@@ -1,437 +1,450 @@
 require 'test_helper'
 
 class DomainTest < ActiveSupport::TestCase
   def setup
     @domain = build(:domain)
   end
 
   test 'automatic SOA creation' do
     @domain.save!
     @domain.reload
     assert_not_nil @domain.soa
   end
 
   test 'increment serial on new record' do
     @domain.save!
     soa = @domain.soa
 
     assert_serial_update soa do
       www = A.new(name: 'www', domain: @domain, content: '1.2.3.4')
       www.save!
     end
   end
 
   test 'increment serial on record update' do
     @domain.save!
     www = A.new(name: 'www', domain: @domain, content: '1.2.3.4')
     www.save!
     soa = @domain.soa.reload
 
     assert_serial_update soa do
       www.content = '1.2.3.5'
       www.save!
     end
   end
 
   test 'uniqueness of records' do
     @domain.save!
     rec = Record.new(type: 'A', name: 'www', domain: @domain, content: '1.2.3.4')
     rec.save!
     assert_empty rec.errors
 
     rec2 = Record.new(type: 'A', name: 'www', domain: @domain, content: '1.2.3.4')
     assert_raises(ActiveRecord::RecordInvalid) { rec2.save! }
     assert_not_empty rec2.errors[:name]
 
     rec3 = Record.new(type: 'A', name: 'www2', domain: @domain, content: '1.2.3.4')
     rec3.save!
     assert_empty rec3.errors
 
     rec4 = Record.new(type: 'A', name: 'www', domain: @domain, content: '1.2.3.5')
     rec4.save!
     assert_empty rec4.errors
 
     rec5 = Record.new(type: 'AAAA', name: 'www', domain: @domain, content: '2001:0db8:85a3:0000:0000:8a2e:0370:7334')
     rec5.save!
     assert_empty rec5.errors
   end
 
   test 'automatic NS creation' do
     @domain.save!
     @domain.reload
     assert_equal WebDNS.settings[:default_ns].sort,
                  @domain.records.where(type: 'NS').pluck(:content).sort
   end
 
   test 'increment serial on record destroy' do
     @domain.save!
     www = A.new(name: 'www', domain: @domain, content: '1.2.3.4')
     www.save!
     soa = @domain.soa.reload
 
     assert_serial_update soa do
       www.destroy!
     end
   end
 
+  test 'do not allow other record types when there is a cname' do
+    @domain.save!
+    name = 'mysupername'
+
+    cname = CNAME.new(name: name, domain: @domain, content: 'whocares')
+    cname.save!
+    assert_empty cname.errors
+
+    www = A.new(name: name, domain: @domain, content: '1.2.3.4')
+    assert_raises(ActiveRecord::RecordNotSaved) { www.save! }
+    assert_not_empty www.errors[:name]
+  end
+
   class SlaveDomainTest < ActiveSupport::TestCase
     def setup
       @domain = build(:slave)
     end
 
     test 'saves' do
       @domain.save
 
       assert_empty @domain.errors
     end
 
     test 'automatic SOA creation' do
       @domain.save!
       @domain.reload
       assert_not_nil @domain.soa
       assert_equal 1, @domain.soa.serial
     end
 
     test 'validates master' do
       @domain.master = 'not-an-ip'
       @domain.save
 
       assert_not_empty @domain.errors['master']
     end
 
     test 'no records are allowed for users' do
       @domain.save!
       rec = build(:a, domain_id: @domain.id)
 
       assert_not rec.valid?
       assert_not_empty rec.errors[:type]
     end
   end
 
   class StatesDomainTest < ActiveSupport::TestCase
     def setup
       @domain = build(:domain)
       @policy = DnssecPolicy.all[0]
     end
 
     test 'domain lifetime' do
       assert_equal 'initial', @domain.state
 
       # Create
       assert_jobs do
         @domain.save! # user triggered
         assert_equal 'pending_install', @domain.state
       end
       @domain.installed # job triggered
       assert_equal 'operational', @domain.state
 
       # Convert to dnssec (sign)
       assert_jobs do
         @domain.dnssec = true
         @domain.dnssec_policy = @policy
         @domain.dnssec_parent = @domain.name.split('.', 2).last
         @domain.dnssec_parent_authority = 'test_authority'
         @domain.save!
 
         # After commit is not triggered in tests,
         # so we have to trigger it manually
         @domain.send(:after_commit_event)
 
         assert_equal 'pending_signing', @domain.state
       end
 
       assert_jobs do
         assert @domain.signed # job triggered
         assert_equal 'wait_for_ready', @domain.state
       end
 
       # Convert to dnssec (publish ds)
       assert_jobs do
         assert @domain.push_ds(['dss1', 'dss2']) # triggered by ds-schedule script
         assert_equal 'pending_ds', @domain.state
       end
       assert @domain.converted # job triggered
       assert_equal 'operational', @domain.state
 
       # KSK rollover
       assert_jobs do
         assert @domain.push_ds(['dss3', 'dss4']) # triggered by ds-schedule script
         assert_equal 'pending_ds_rollover', @domain.state
       end
       assert @domain.complete_rollover # job triggered
       assert_equal 'operational', @domain.state
 
       # Convert to plain
       assert_jobs do
         assert @domain.plain_convert # user triggered
         assert_equal 'pending_plain', @domain.state
       end
       assert @domain.converted # job triggered
       assert_equal 'operational', @domain.state
 
       # Remove
       assert_jobs do
         assert @domain.remove # user triggered
         assert_equal 'pending_remove', @domain.state
       end
       assert @domain.cleaned_up # job triggered
       assert_equal 'destroy', @domain.state
     end
 
     test 'domain lifetime #full-destroy' do
       assert_equal 'initial', @domain.state
 
       # Create
       assert_jobs do
         @domain.save! # user triggered
         assert_equal 'pending_install', @domain.state
       end
       @domain.installed # job triggered
       assert_equal 'operational', @domain.state
 
       # Convert to dnssec (sign)
       assert_jobs do
         @domain.dnssec = true
         @domain.dnssec_policy = @policy
         @domain.dnssec_parent = @domain.name.split('.', 2).last
         @domain.dnssec_parent_authority = 'test_authority'
         @domain.save!
 
         # After commit is not triggered in tests,
         # so we have to trigger it manually
         @domain.send(:after_commit_event)
 
         assert_equal 'pending_signing', @domain.state
       end
 
       assert_jobs do
         assert @domain.signed # job triggered
         assert_equal 'wait_for_ready', @domain.state
       end
 
       # Convert to dnssec (publish ds)
       assert_jobs do
         assert @domain.push_ds(['dss1', 'dss2']) # triggered by ds-schedule script
         assert_equal 'pending_ds', @domain.state
       end
       assert @domain.converted # job triggered
       assert_equal 'operational', @domain.state
 
       # KSK rollover
       assert_jobs do
         assert @domain.push_ds(['dss3', 'dss4']) # triggered by ds-schedule script
         assert_equal 'pending_ds_rollover', @domain.state
       end
       assert @domain.complete_rollover # job triggered
       assert_equal 'operational', @domain.state
 
       # Full Remove (Drops DS records)
       assert_jobs do
         assert @domain.full_remove # user triggered
         assert_equal 'pending_ds_removal', @domain.state
       end
 
       assert_jobs do
         assert @domain.remove # job triggered
         assert_equal 'pending_remove', @domain.state
       end
       assert @domain.cleaned_up # job triggered
       assert_equal 'destroy', @domain.state
     end
   end
 
   class DsDomainTest < ActiveSupport::TestCase
     def setup
       @domain = create(:domain)
       @ds = [
         '31406 8 1 189968811e6eba862dd6c209f75623d8d9ed9142',
         '31406 8 2 f78cf3344f72137235098ecbbd08947c2c9001c7f6a085a17f518b5d8f6b916d',
       ]
       @child = "dnssec.#{@domain.name}"
       @extra = DS.create(domain: @domain, name: @child, content: 'other')
     end
 
     test 'add ds records' do
       Domain.replace_ds(@domain.name, @child, @ds)
       @extra.save! # Should be deleted
 
       assert_equal @ds.size, DS.where(name: "dnssec.#{@domain.name}").count
       @ds.each { |ds|
         assert_equal 1, DS.where(name: "dnssec.#{@domain.name}", content: ds).count
       }
     end
 
     test 'remove ds records' do
       Domain.replace_ds(@domain.name, @child, [])
 
       assert_equal 0, DS.where(name: "dnssec.#{@domain.name}").count
     end
 
     test 'check if child is a valid subdomain' do
       assert_raise Domain::NotAChild do
         Domain.replace_ds(@domain.name, 'dnssec.example.net', @ds)
       end
     end
 
   end
 
   class BulkTest < ActiveSupport::TestCase
     def setup
       @domain = create(:domain)
       @a = create(:a, domain: @domain)
       @aaaa = create(:aaaa, domain: @domain)
       @new = build(:mx, domain: @domain)
 
     end
 
     def valid_changes
       @valid_changes ||= begin
                            {}.tap { |c|
                              c[:deletes] = [@a.id]
                              c[:changes] = { @aaaa.id => { content: '::42' }}
                              c[:additions] = { 1 => @new.as_bulky_json }
                            }
                          end
     end
 
     def invalid_changes
       @invalid_changes ||= begin
                              {}.tap { |c|
                                c[:deletes] = [Record.maximum(:id) + 1]
                                c[:changes] = { @aaaa.id => { content: '1.2.3.4' }}
                                c[:additions] = { 1 => @new.as_bulky_json.update(prio: -1) }
                              }
                            end
     end
 
     test 'apply changes not' do
       ops, err = @domain.bulk invalid_changes
 
       assert_not_empty err
       assert_includes err[:deletes][Record.maximum(:id) + 1], 'record not found'
       assert_includes err[:changes][@aaaa.id], 'not a valid IPv6'
       assert_includes err[:additions][1], 'not a valid DNS priority'
     end
 
     test 'apply changes' do
       ops, err = @domain.bulk valid_changes
 
       @domain.reload
       @aaaa.reload
 
       assert_empty err
       assert_empty @domain.records.where(id: @a.id)
       assert_equal '::42', @aaaa.content
       assert_equal 1, @domain.records.where(type: :mx).count
       assert_equal 1, ops[:additions].size
       assert_equal 1, ops[:changes].size
       assert_equal 1, ops[:deletes].size
     end
   end
 
   class ApiBulkTest < ActiveSupport::TestCase
     def setup
       @domain = create(:domain)
       @a = create(:a, domain: @domain)
       @aaaa = create(:aaaa, domain: @domain, content: '::42')
       @new = build(:mx, domain: @domain)
       @upsert_txt = build(:txt, domain: @domain)
 
     end
 
     def valid_changes
       @valid_changes ||= begin
                            {}.tap { |c|
                              c[:deletes] = [@a.to_api]
                              c[:additions] = [@new.to_api]
                              c[:upserts] = [@upsert_txt.to_api]
                            }
                          end
     end
 
     test 'apply changes' do
       ops, err = @domain.api_bulk valid_changes
 
       @domain.reload
       @aaaa.reload
 
       assert_empty err
       assert_empty @domain.records.where(id: @a.id)
       assert_equal '::42', @aaaa.content
       assert_equal 1, @domain.records.where(type: :mx).count
       assert_equal 2, ops[:additions].size # upsert is accounted as in addition
       assert_equal 1, ops[:deletes].size
 
     end
 
     test 'additions is invalid' do
       changes = {
         additions: [ @new.to_api.update(prio: -1) ]
       }
 
       ops, err = @domain.api_bulk changes
 
       assert_not_empty err
       assert_includes err[:additions].first[:error], 'not a valid DNS priority'
     end
 
 
     test 'delete not exists' do
       changes = Hash[
         :deletes, [{name: 'nx', type: 'TXT', content: 'not-exists'}]
       ]
 
       ops, err = @domain.api_bulk changes
 
       assert_empty ops
       assert_equal 1, err[:deletes].size
     end
 
     test 'upsert does not exist (single record)' do
       a1 = create(:a, domain: @domain, name: 'rr', content: '127.0.0.1')
 
       rr_name = "rr.#{@domain.name}"
       changes = Hash[
         :upserts, [{name: rr_name, type: 'A', content: '127.0.0.3'}]
       ]
 
       ops, err = @domain.api_bulk changes
 
       assert_empty err
       assert_equal 1, @domain.records.where(name: rr_name, type: 'A').count
       assert_equal '127.0.0.3', @domain.records.find_by(name: rr_name, type: 'A').content
     end
 
     test 'upsert does not exist (multiple records)' do
       a1 = create(:a, domain: @domain, name: 'rr', content: '127.0.0.1')
       a2 = create(:a, domain: @domain, name: 'rr', content: '127.0.0.2')
 
       rr_name = "rr.#{@domain.name}"
       changes = Hash[
         :upserts, [{name: rr_name, type: 'A', content: '127.0.0.3'}]
       ]
 
       ops, err = @domain.api_bulk changes
 
       assert_empty err
       assert_equal 1, @domain.records.where(name: rr_name, type: 'A').count
       assert_equal '127.0.0.3', @domain.records.find_by(name: rr_name, type: 'A').content
     end
 
     test 'upsert exists' do
       a1 = create(:a, domain: @domain, name: 'rr', content: '127.0.0.1')
 
       rr_name = "rr.#{@domain.name}"
       changes = Hash[
         :upserts, [{name: rr_name, type: 'A', content: '127.0.0.1'}]
       ]
 
       ops, err = @domain.api_bulk changes
 
       assert_empty err
       assert_empty ops # upsert is a noop
       assert_equal 1, @domain.records.where(name: rr_name, type: 'A').count
       assert_equal '127.0.0.1', @domain.records.find_by(name: rr_name, type: 'A').content
     end
   end
 end