📝 BER Basic Encoding Rules in ASN.1 (9 MCQs)
📖 From Data Communication and Networks • 27. Network Management • 9 questions available
What is BER Basic Encoding Rules in ASN.1?
BER is a set of rules that defines how ASN.1-defined data structures are converted into binary format for transmission, using tag-length-value encoding to ensure interoperability by specifying exact byte layouts regardless of platform or programming language.
📝 All BER Basic Encoding Rules in ASN.1 MCQs
Q1. In the sendResponse method, which of the following statements best explains why an IOException might be printed on line 61?
📖 Explanation: The IOException is triggered when the underlying socket cannot transmit the datagram. If the DatagramSocket has been closed earlier, any attempt to send will throw an IOException, which the catch block reports on line 61. Other options such as a null response string or an out‑of‑range port would result in different exceptions or compile‑time errors, not the specific IOException caught here.
Q2. If the getRequest method extracts the client IP address before extracting the client port number, what logical error could this cause in the subsequent sendResponse call?
📖 Explanation: Extracting the IP address before the port number does not change the values themselves, but if the programmer mistakenly treats the first extracted field as the port, the numeric IP bytes could be interpreted as a port, causing the response to be sent to an incorrect endpoint. This logical mix‑up would result in the client never receiving the reply, even though the IP is correct.
Q3. Considering the infinite while(true) loop in main, what is the most likely long‑term effect on system resources if each iteration creates a new UDPServer instance without explicit cleanup?
📖 Explanation: Each loop iteration creates a new UDPServer object that holds a reference to the same DatagramSocket. After the iteration ends, the object becomes eligible for garbage collection because no further references exist. The JVM’s collector will eventually reclaim its memory, so the program does not accumulate socket descriptors or memory indefinitely. Therefore the most likely long‑term effect is no resource exhaustion, not a memory leak.
Q4. Which of the following best contrasts the responsibilities of the UDPServer constructor with those of the getRequest method?
📖 Explanation: The constructor’s sole purpose is to receive the DatagramSocket reference and store it in an instance variable, preparing the object for later use. In contrast, the getRequest method performs all I/O operations: it creates buffers, receives the packet, extracts data, and records the client’s address and port. Thus the two components have distinct, non‑overlapping responsibilities.
Q5. How would increasing the size of the receive buffer (line 22) from 1024 bytes to 4096 bytes most likely affect the server's ability to handle larger client messages?
📖 Explanation: Increasing the receive buffer from 1024 to 4096 bytes expands the maximum payload the server can accommodate in a single UDP datagram. When a client sends a message larger than the original limit, the additional space prevents truncation, allowing the full message to be captured and processed. The change does not inherently affect processing speed or protocol limits.
Q6. If the DatagramSocket is created with a specific port number versus using the no‑argument constructor, which of the following statements is true?
📖 Explanation: When a DatagramSocket is instantiated with an explicit port number, the operating system attempts to bind that socket to the given port. If the port is already in use, the constructor throws a BindException, indicating the conflict. Using the no‑argument constructor lets the system automatically select an available port, avoiding the binding failure.
Q7. When converting the received byte array to a String (line 26), which principle ensures that the original message is reconstructed correctly across different platforms?
📖 Explanation: Using a standard, platform‑independent charset such as UTF‑8 when converting the received byte array to a String guarantees that the same sequence of bytes is interpreted identically on any machine. Relying on the default charset can produce mismatched characters if the client and server have different locale settings, leading to corrupted messages.
Q8. Suppose you need to add logging of every request and response without altering the existing method signatures. Which design change best synthesizes this requirement while preserving encapsulation?
📖 Explanation: Injecting a Logger instance through the constructor preserves encapsulation because the UDPServer class does not need to know the details of logging implementation. The logger can be stored as a private field and invoked inside getRequest and sendResponse, allowing centralized control of log formatting and destination without altering the method signatures or breaking existing code.
Q9. On which line of the code does the DatagramSocket get instantiated?
📖 Explanation: The DatagramSocket is instantiated on line 68 with the expression new DatagramSocket(port). This line creates the socket bound to the user‑provided port, enabling the server to listen for incoming UDP datagrams. No other line in the shown excerpt performs socket creation.