2018 Communications Engineer Examination, Internet Technology Afternoon Real Question Analysis 1. Database System (20 points) The E-R diagram of the staff scientific research management database system of a company is shown in Figure 7, in which the underlined attribute is the entity identifier.The relational model of the database system is as follows: Departments (Departments, Departments, Offices) Employees (employee number, name, sex, age, specialty, title, Department number) Project (project number, project name, project funds, project source, person in charge) Participation (Employee Number, Project Number) [Question 1] (4 points) The database system is the system after introducing the database into the computer system.Which four parts does it consist of? [Answer] Database, database users, computer hardware system and computing software system. [Question 2] (5 points) (1) The relational database system is a database system supporting the relational model. Please write out three kinds of integrity constraints of the relational model. Relevant data structure, operation set and integrity constraints of relational relationship model. Relational Integrity Constraints: Entity Integrity, Reference Integrity, Userdefined Integrity. (2) Among the three types of integrity constraints in relational models, which type of integrity constraints is related to the value of foreign keys? Reference Integrity Constraints (3) What are the attributes of foreign keys in the above-mentioned "employee" relationship model? Department Number [Question 3] (9 points) Referring to the above four relational patterns, complete the following topics with SQL statements. (1) Search the names, specialties and departments of employees whose number is 20180208. (2) To inquire the Department number, department name and the number of employees of each department. (3) Definition includes the project name, project funds view vProject, sorted in descending order according to project funds. [Answer] Select name, major, department name from department, where Department of staff. Department number = staff. Department number and work number = 20180208' Select department. Department number, Department name, count (*) AS number of employees from department, where Department of employees. Department number = employees. Department number; Create view vProject from project order by project funding DESC [Question 4] (2 points) Transaction is a unit of work executed in a database system. It is a set of operation sequences defined by users.Write down any two of the four characteristics of a transaction. Atomicity, consistency, isolation, persistence OSI Security Reference Model (20 points) OSI reference model is the theoretical basis for researching, designing new computer network systems and evaluating and improving existing systems. It is also the basis for understanding and realizing network security.OSI Security Reference Model focuses on security attacks, security mechanisms and security services. Figure 4 [Question 1] (4 points) Security attacks are divided into passive attacks and active attacks, as shown in Figure 4.Write down four categories of active attacks. Interruption, tampering, forgery and attack [Question 2] (4 points) In order to meet the security and secrecy requirements of the network system, OSI security architecture has set up seven types of security services and adopted eight security mechanisms.Please write out four security services that depend on the security mechanism of "digital signature". Completeness, Peer-to-Peer Entity Authentication, Information Source Authentication, Non-repudiation [Question 3] (5 points) (1) Intrusion detection is used to detect violations of security policies in computer networks.Write down: What kind of intrusion detection technology is the problem of how to establish "activity profile" and how to design statistical algorithms so as not to regard normal operations as "intrusion" or ignore the real "intrusion" behavior? Anomaly Detection (2) Table 4 lists the names of three malicious programs and Table 5 lists the descriptions of three malicious programs.Please write the description of the malicious program corresponding to the name of the malicious program (the corresponding relationship between serial number and number, for example: 4 D).Table 4 Malicious Program Name Table 5 Malicious Program Description; [Answer] C, B, A [Question 4] (7 points) Public key cryptosystem has two k

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