diff --git a/School/Analyse/Layers/3. Network Layer.md b/School/Analyse/Layers/3. Network Layer.md
index 13d99ca..78a29aa 100644
--- a/School/Analyse/Layers/3. Network Layer.md	
+++ b/School/Analyse/Layers/3. Network Layer.md	
@@ -113,5 +113,16 @@ Example 144.24.13.172/**20 (20 bits used for network ID)**
 Also the following addresses are not used as a valid and unique IPv4 Addresses:
 
 10.0.0.0 - 10.255.255.255/8 (16.777.216 hosts)
-172.
+172.16.0.0 - 172.31.255.255/12 (1.048.576 hosts)
+192.168.0.0 - 192.168.255.255/16 (65.536 hosts)
+
+We use these IP addresses as local addresses. The local addresses are translated into a global IP when sending messages to a host in a other network. This translation process is called NAT.
+
+### Scarce IP address problem
+With 32 bits, the maximum possible IPv4 addressed is 2^32 = 4 billion
+**We need more addresses.**
+
+##  IPV6
+Solution
+