diff --git a/gsd-questions.tex b/gsd-questions.tex
index fffd060..61ae0e8 100755
--- a/gsd-questions.tex
+++ b/gsd-questions.tex
@@ -115,6 +115,37 @@ such a traversal?
 \fi
 
 \section{Networking}
+\subsection{Protocol Stacks}
+Explain the major differences between the network protocols UDP, TCP and IP.
+
+\ifdefined\loesung
+\textcolor{red}{
+	{\bf Solution}: UDP is connectionless, offers no error correction etc., data is sent directly without handshake, typically used for real-time protocols. TCP is connection-oriented, offers error correction, flow control (also congestion control), bidirectional reliable data transfer. IP is on a different layer (Layer 3 / network layer) compared to TCP and UDP (Layer 4 / transport layer), IP is connectionless transports datagrams between endpoints, supports routing etc.}
+\fi
+
+\subsection{TCP Characteristics}
+Fill the gaps with appropriate values for the corresponding TCP header fields:
+
+\begin{figure}[htb]
+	\includegraphics[width=0.9\columnwidth]{images/tcp-handshake-and-flowcontrol.png}
+\end{figure}
+
+\ifdefined\loesung
+\textcolor{red}{
+	{\bf Solution}: 2: Flags = SYN+ACK, 3: Flags = ACK, 5: ACK = sa+900, Data-Length = 400 (according to ACK in 7), 6: SEQ = sa+900, Data-Length = 100 (due to limit in (Receive) Window Size), 7: sa+1000.}
+\fi
+
+\subsection{Network Addresses}
+Insert the Layer 2 and Layer 3 addresses used the following transfer from Computer A to Computer B. How many IP addresses can exist in the subnet Computer B is placed in? What is the network address of this subnet?
+
+\begin{figure}[htb]
+	\includegraphics[width=0.9\columnwidth]{images/mac-address.png}
+\end{figure}
+
+\ifdefined\loesung
+\textcolor{red}{
+	{\bf Solution}: Source IP: 1.1.1.10 (not 1.1.1.10/24), Destination IP: 2.2.15.100 (not 2.2.15.100/21), Source MAC: 11:22:33:44:55:66, Destination MAC: aa:bb:cc:dd:ee:ff (not 33:44:55:66:77:88). Number of hosts in /21 IPv4 subnet = 2046 ($2^{32-21}-2$). Network address of the IP subnet of Computer B: 2.2.8.0/21.}
+\fi
 
 \section{Regular Expressions and Shells}
 \subsection{Regular Expression}
diff --git a/images/mac-address.png b/images/mac-address.png
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diff --git a/images/tcp-handshake-and-flowcontrol.png b/images/tcp-handshake-and-flowcontrol.png
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