diff --git a/app/controllers/private_controller.rb b/app/controllers/private_controller.rb
index 68b859f..b9b08b0 100644
--- a/app/controllers/private_controller.rb
+++ b/app/controllers/private_controller.rb
@@ -1,39 +1,38 @@
 class PrivateController < ApplicationController
   # This a private trusted API
   skip_before_action :verify_authenticity_token
 
   # PUT /replace_ds
   def replace_ds
     parent, child, ds = replace_ds_params.values_at(:parent, :child, :ds)
     Domain.replace_ds(parent, child, ds)
 
     render json: { ok: true }
   rescue ActiveRecord::RecordNotFound
     render json: { ok: false, msg: 'Domain not found!' }
   end
 
   # PUT /trigger_event
   def trigger_event
     result = Domain
              .find_by_name(action_params[:domain])
              .fire_state_event(action_params[:event], params[:args])
     render json: { ok: result }
   end
 
   private
 
   def action_params
     params.require(:domain)
     params.require(:event)
     params.permit(:domain, :event, args: [])
   end
 
   def replace_ds_params
     params.require(:parent)
     params.require(:child)
-    params.require(:ds)
     params.permit(ds: [])
 
     params
   end
 end
diff --git a/app/models/domain.rb b/app/models/domain.rb
index 0edddca..7a248cf 100644
--- a/app/models/domain.rb
+++ b/app/models/domain.rb
@@ -1,309 +1,310 @@
 class Domain < ActiveRecord::Base
   class NotAChild < StandardError; end
   self.inheritance_column = :nx
 
   # List all supported domain types.
   def self.domain_types
     [
       'NATIVE',
       'MASTER',
       'SLAVE',
     ]
   end
 
   # List domain types that can be created.
   def self.allowed_domain_types
     domain_types - WebDNS.settings[:prohibit_domain_types]
   end
 
   # List parent authorities
   def self.dnssec_parent_authorities
     WebDNS.settings[:dnssec_parent_authorities].keys.map(&:to_s)
   end
 
   # Fire event after transaction commmit
   # Changing state inside a hook messes things up,
   # this trick handles that
   attr_accessor :fire_event
 
   belongs_to :group
   has_many :jobs
   has_many :records
   # BUG in bump_serial_trigger
   has_one :soa, -> { unscope(where: :type).where(type: 'soa') }, class_name: SOA
   belongs_to :dnssec_policy
 
   validates :group_id, presence: true
   validates :name, uniqueness: true, presence: true
   validates :type, presence: true, inclusion: { in: domain_types }
   validates :master, presence: true, ipv4: true, if: :slave?
 
   validates :dnssec, inclusion: { in: [false] }, unless: :dnssec_elegible?
   validates :dnssec_parent_authority, inclusion: { in: dnssec_parent_authorities }, if: :dnssec?
   validates :dnssec_parent, hostname: true, if: :dnssec?
   validates :dnssec_policy_id, presence: true, if: :dnssec?
 
   after_create :generate_soa
   after_create :generate_ns
 
   after_create :install
   before_save :check_convert
   before_save :check_dnssec_parent_authority, if: :dnssec?
   after_commit :after_commit_event
 
   attr_writer :serial_strategy
 
   def self.dnssec_progress(current_state)
     progress = [
       :pending_signing, # 1/3
       :wait_for_ready,  # 2/3
       :pending_ds]      # 3/3
     idx = progress.index(current_state.to_sym)
     return if idx.nil?
 
     [idx+1, progress.size].join('/')
   end
 
   state_machine initial: :initial do
     after_transition(any => :pending_install) { |domain, _t| Job.add_domain(domain) }
     after_transition(any => :pending_remove) { |domain, _t| Job.shutdown_domain(domain) }
     after_transition(any => :pending_ds_removal) { |domain, _t| Job.dnssec_drop_ds(domain) }
     after_transition(any => :pending_signing) { |domain, _t| Job.dnssec_sign(domain) }
     after_transition(any => :wait_for_ready) { |domain, _t| Job.wait_for_ready(domain) }
     after_transition(any => :pending_ds) { |domain, t| Job.dnssec_push_ds(domain, *t.args) }
     after_transition(any => :pending_ds_rollover) { |domain, t| Job.dnssec_rollover_ds(domain, *t.args) }
     after_transition(any => :pending_plain) { |domain, _t| Job.convert_to_plain(domain) }
     after_transition(any => :destroy) { |domain, _t| domain.destroy }
 
     # User events
     event :install do
       transition initial: :pending_install
     end
 
     event :dnssec_sign do
       transition operational: :pending_signing
     end
 
     event :signed do
       transition pending_signing: :wait_for_ready
     end
 
     event :push_ds do
       transition wait_for_ready: :pending_ds, operational: :pending_ds_rollover
     end
 
     event :plain_convert do
       transition operational: :pending_plain
     end
 
     event :remove do
       transition [:operational, :pending_ds_removal] => :pending_remove
     end
 
     event :full_remove do
       transition operational: :pending_ds_removal
     end
 
     # Machine events
     event :installed do
       transition pending_install: :operational
     end
 
     event :converted do
       transition [:pending_ds, :pending_plain] => :operational
     end
 
     event :complete_rollover do
       transition pending_ds_rollover: :operational
     end
 
     event :cleaned_up do
       transition pending_remove: :destroy
     end
 
     event :ksk_rollover_detected do
       transition operational: :ksk_rollover
     end
   end
 
   # Returns true if this domain is elegigble for DNSSEC
   def dnssec_elegible?
     return false if slave?
 
     true
   end
 
   # Returns the zone serial if a SOA record exists
   def serial
     return if !soa
 
     soa.serial
   end
 
   # Get the zone's serial strategy.
   #
   # Returns one of the supported serial strategies.
   def serial_strategy
     @serial_strategy ||= WebDNS.settings[:serial_strategy]
   end
 
   # Returns true if this a reverse zone.
   def reverse?
     name.end_with?('.in-addr.arpa') || name.end_with?('.ip6.arpa')
   end
 
   # Returns true if this a ENUM zone.
   def enum?
     name.end_with?('.e164.arpa')
   end
 
   # Returns true if this is a slave zone.
   def slave?
     type == 'SLAVE'
   end
 
   # Compute subnet for reverse records
   def subnet
     return if not reverse?
 
     if name.end_with?('.in-addr.arpa')
       subnet_v4
     elsif name.end_with?('.ip6.arpa')
       subnet_v6
     end
   end
 
   def self.replace_ds(parent, child, records)
+    records ||= []
     parent = find_by_name!(parent)
     fail NotAChild if not child.end_with?(parent.name)
 
     existing = parent.records.where(name: child, type: 'DS')
     recs = records.map { |rec| DS.new(domain: parent, name: child, content: rec) }
 
     ActiveRecord::Base.transaction do
       existing.destroy_all
       recs.map(&:save!)
     end
   end
 
   # Apply bulk to operations to the zones
   #
   # 1) Deletions
   # 2) Changes
   # 3) Additions
   def bulk(opts)
     deletes = opts[:deletes] || []
     changes = opts[:changes] || {}
     additions = opts[:additions] || {}
     errors = Hash.new { |h, k| h[k] = {} }
 
     ActiveRecord::Base.transaction do
       # Deletes
       to_delete = records.where(id: deletes).index_by(&:id)
       deletes.each { |rec_id|
         if rec = to_delete[Integer(rec_id)]
           rec.destroy
           next
         end
 
         errors[:deletes][rec_id] = 'Deleted record not found'
       }
 
       # Changes
       to_change = records.where(id: changes.keys).index_by(&:id)
       changes.each {|rec_id, changes|
         binding
         if rec = to_change[Integer(rec_id)]
           errors[:changes][rec_id] = rec.errors.full_messages.join(', ') if !rec.update(changes)
           next
         end
 
         errors[:changes][rec_id] = 'Changed record not found'
       }
 
       # Additions
       additions.each { |inc, attrs|
         rec = records.new(attrs)
         errors[:additions][inc] = rec.errors.full_messages.join(', ') if !rec.save
       }
 
       raise ActiveRecord::Rollback if errors.any?
     end
 
     errors
   end
 
   private
 
   def subnet_v4
     # get ip octets (remove .in-addr.arpa)
     octets = name.split('.')[0...-2].reverse
     return if octets.any? { |_| false }
 
     mask = 8 * octets.size
     octets += [0, 0, 0, 0]
 
     ip = IPAddr.new octets[0, 4].join('.')
 
     [ip, mask].join('/')
   end
 
   def subnet_v6
     nibbles = name.split('.')[0...-2].reverse
     return if nibbles.any? { |_| false }
 
     mask = 4 * nibbles.size
     nibbles += [0] * 32
 
     ip = IPAddr.new nibbles[0, 32].in_groups_of(4).map(&:join).join(':')
 
     [ip, mask].join('/')
   end
 
   # Hooks
 
   def generate_soa
     soa_record = SOA.new(domain: self)
 
     soa_record.save!
   end
 
   def generate_ns
     return if slave?
     return if WebDNS.settings[:default_ns].empty?
 
     WebDNS.settings[:default_ns].each { |ns|
       Record.find_or_create_by!(domain: self, type: 'NS', name: '', content: ns)
     }
   end
 
   def check_convert
     return if !dnssec_changed?
 
     event = dnssec ? :dnssec_sign : :plain_convert
     if state_events.include?(event)
       self.fire_event = event # Schedule event for after commit
       return true
     end
 
     errors.add(:dnssec, 'You cannot modify dnssec settings in this state!')
     false
   end
 
   def check_dnssec_parent_authority
     cfg = WebDNS.settings[:dnssec_parent_authorities][dnssec_parent_authority.to_sym]
     return if !cfg[:valid]
 
     return true if cfg[:valid].call(dnssec_parent)
 
     errors.add(:dnssec_parent_authority, 'Parent zone is not accepted for the selected parent authority!')
     false
   end
 
   def after_commit_event
     return if !fire_event
 
     fire_state_event(fire_event)
     self.fire_event = nil
   end
 end