#2 ぼちぼち

backend/app/models/ip_address.rb

@@ -0,0 +1,6 @@
+class IpAddress < ApplicationRecord
+  validates :ip_address, presence: true, length: { maximum: 16 }
+  validates :banned, inclusion: { in: [true, false] }
+
+  has_many :users
+end