diff --git a/DnsServerCore/Dns/Zones/AuthZone.cs b/DnsServerCore/Dns/Zones/AuthZone.cs
index 97857eee..6c86bbd0 100644
--- a/DnsServerCore/Dns/Zones/AuthZone.cs
+++ b/DnsServerCore/Dns/Zones/AuthZone.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using TechnitiumLibrary.IO;
 using TechnitiumLibrary.Net.Dns;
diff --git a/DnsServerCore/Dns/Zones/AuthZoneInfo.cs b/DnsServerCore/Dns/Zones/AuthZoneInfo.cs
index b85e3ef9..c4cd0a43 100644
--- a/DnsServerCore/Dns/Zones/AuthZoneInfo.cs
+++ b/DnsServerCore/Dns/Zones/AuthZoneInfo.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using System.IO;
 using TechnitiumLibrary.IO;
diff --git a/DnsServerCore/Dns/Zones/AuthZoneManager.cs b/DnsServerCore/Dns/Zones/AuthZoneManager.cs
index 7d3106b6..c51dded6 100644
--- a/DnsServerCore/Dns/Zones/AuthZoneManager.cs
+++ b/DnsServerCore/Dns/Zones/AuthZoneManager.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Net;
diff --git a/DnsServerCore/Dns/Zones/BlockListZoneManager.cs b/DnsServerCore/Dns/Zones/BlockListZoneManager.cs
index 9ff1891b..4c70ca8c 100644
--- a/DnsServerCore/Dns/Zones/BlockListZoneManager.cs
+++ b/DnsServerCore/Dns/Zones/BlockListZoneManager.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
diff --git a/DnsServerCore/Dns/Zones/CacheZone.cs b/DnsServerCore/Dns/Zones/CacheZone.cs
index 9f5343a3..c1547018 100644
--- a/DnsServerCore/Dns/Zones/CacheZone.cs
+++ b/DnsServerCore/Dns/Zones/CacheZone.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using TechnitiumLibrary.IO;
 using TechnitiumLibrary.Net.Dns;
diff --git a/DnsServerCore/Dns/Zones/CacheZoneManager.cs b/DnsServerCore/Dns/Zones/CacheZoneManager.cs
index bd9ead33..c47a9cd4 100644
--- a/DnsServerCore/Dns/Zones/CacheZoneManager.cs
+++ b/DnsServerCore/Dns/Zones/CacheZoneManager.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using TechnitiumLibrary.Net.Dns;
 using TechnitiumLibrary.Net.Dns.ResourceRecords;
diff --git a/DnsServerCore/Dns/Zones/DnsResourceRecordExtension.cs b/DnsServerCore/Dns/Zones/DnsResourceRecordExtension.cs
index 02468a76..265470c0 100644
--- a/DnsServerCore/Dns/Zones/DnsResourceRecordExtension.cs
+++ b/DnsServerCore/Dns/Zones/DnsResourceRecordExtension.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using System.Net;
 using System.Net.Sockets;
diff --git a/DnsServerCore/Dns/Zones/DnsResourceRecordInfo.cs b/DnsServerCore/Dns/Zones/DnsResourceRecordInfo.cs
index fc98d714..6b8c03b3 100644
--- a/DnsServerCore/Dns/Zones/DnsResourceRecordInfo.cs
+++ b/DnsServerCore/Dns/Zones/DnsResourceRecordInfo.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using System.IO;
 using TechnitiumLibrary.Net.Dns;
diff --git a/DnsServerCore/Dns/Zones/PrimaryZone.cs b/DnsServerCore/Dns/Zones/PrimaryZone.cs
index adfbc3fd..e6b96725 100644
--- a/DnsServerCore/Dns/Zones/PrimaryZone.cs
+++ b/DnsServerCore/Dns/Zones/PrimaryZone.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using TechnitiumLibrary.Net.Dns;
 using TechnitiumLibrary.Net.Dns.ResourceRecords;
diff --git a/DnsServerCore/Dns/Zones/SecondaryZone.cs b/DnsServerCore/Dns/Zones/SecondaryZone.cs
index 55c7af35..ba4ecbb9 100644
--- a/DnsServerCore/Dns/Zones/SecondaryZone.cs
+++ b/DnsServerCore/Dns/Zones/SecondaryZone.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using TechnitiumLibrary.Net.Dns;
 using TechnitiumLibrary.Net.Dns.ResourceRecords;
diff --git a/DnsServerCore/Dns/Zones/StubZone.cs b/DnsServerCore/Dns/Zones/StubZone.cs
index fc509130..d23ca23c 100644
--- a/DnsServerCore/Dns/Zones/StubZone.cs
+++ b/DnsServerCore/Dns/Zones/StubZone.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using TechnitiumLibrary.Net.Dns;
 using TechnitiumLibrary.Net.Dns.ResourceRecords;
diff --git a/DnsServerCore/Dns/Zones/SubDomainZone.cs b/DnsServerCore/Dns/Zones/SubDomainZone.cs
index 49618502..968e5c9c 100644
--- a/DnsServerCore/Dns/Zones/SubDomainZone.cs
+++ b/DnsServerCore/Dns/Zones/SubDomainZone.cs
@@ -1,4 +1,23 @@
-namespace DnsServerCore.Dns.Zones
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+namespace DnsServerCore.Dns.Zones
 {
     public sealed class SubDomainZone : AuthZone
     {
diff --git a/DnsServerCore/Dns/Zones/Zone.cs b/DnsServerCore/Dns/Zones/Zone.cs
index eedcce1e..2d86caed 100644
--- a/DnsServerCore/Dns/Zones/Zone.cs
+++ b/DnsServerCore/Dns/Zones/Zone.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using TechnitiumLibrary.Net.Dns;
diff --git a/DnsServerCore/Dns/Zones/ZoneTree.cs b/DnsServerCore/Dns/Zones/ZoneTree.cs
index 0bd862f0..cc9a50d5 100644
--- a/DnsServerCore/Dns/Zones/ZoneTree.cs
+++ b/DnsServerCore/Dns/Zones/ZoneTree.cs
@@ -1,4 +1,23 @@
-using System;
+/*
+Technitium DNS Server
+Copyright (C) 2020  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
 using System.Collections.Generic;
 using System.Text;
 using System.Threading;