1. Which operation efficiency can be significantly improved by database indexing?
Correct Answer: A
A SELECT
B INSERT INTO … VALUES …
C UPDATE
D DELETE
2. Database: Which of the following locking methods can provide the best parallel access performance?
Correct Answer: D
A column lock
B table lock
C block lock
D row lock
3. What is the result of omitting the WHERE clause from the DELETE statement?
Correct Answer: B
A DELETE statement will fail because there are no records to delete
B DELETE statement will delete all records from the table
C DELETE statement will prompt the user to delete the standard
D DELETE statement will fail because of a syntax error
4. Which network layer protocol is generally used by raceroute?
Correct Answer: D
A vrrp
B udp
C arp
D icmp
5. Which lsa in the ospf protocol can only be spread in this area?
Correct Answer: A
A 2
B 3
C 5
D 7
6. In the Linux system, which of the following signals cannot be captured?
Correct Answer: B
A SIGHUP
B SIGKILL
C SIGQUIT
D SIGUSR1
7. Under Linux, how to check what process is occupied by a port?
Correct Answer: B
A netstat -an|grep port number
B netstat -tnlp | grep port number
C iostat -an | grep port number
D iostat -dxt | grep port number
8. How to remove duplicate elements from a list?
Correct Answer: B
The A list cannot be deduplicated.
B First convert the list to a deduplicated set, then
first convert the list to a deduplicated tuple in list C, and then list
D. There will be no repetition in the list.
9. What is the difference between Python's List and Tuple?
Correct Answer: A
A lists are mutable, tuples are immutable
B no difference
C limits are different
D lists can be iterated, tuples cannot be iterated
10. What is the correct statement about inheritance of Python classes?
Correct Answer: C
A python class cannot inherit
B can inherit but cannot execute the construction function of the parent class
C can have multiple parent classes
D can only have one parent class
11. Which of the following descriptions about ports are correct?
Correct Answer: ABCD
A FTP uses TCP 20 port
B FTP uses TCP 21 port
C DNS uses TCP 53 port
D DNS uses UDP 53 port
12. Which of the following differences between GET and POST in the http protocol is wrong?
Correct Answer: AC
A They can all be bookmarked and cached
B GET request parameters are placed in the URL
C GET is only used for query requests and cannot be used to request data
D GET should not handle requests for sensitive data
13. A simple website may consist of these three parts: a web server (providing web pages and http services), a background server (such as a java background program, responsible for computing), and a mysql database server (storing user data). However, we know that such a website is also very fragile. Any problems with the above three servers (server problems, or network problems of the server, or problems with the programs running on it) will cause the website to be inaccessible. Obviously, this cannot meet the service commitment of Meituan Dianping to users. Now, assuming that you are the technical manager of the company, what kind of enhancements or improvements do you think you would do to help improve the usability of the website for the above 3 parts? (enumerate as many as possible)
14. From which aspects to evaluate the quality of a hash function? List several common hash functions?
Reference answer: Judgment criteria for the quality of the hash function 1. Efficient and saving CPU can improve concurrency. As an intermediate layer, it is necessary to efficiently calculate the hash according to the key. 2. The conflict is as small as possible, so small that a unique index can be established. 3. As much as possible possible space saving. For example, to store this result in the database and build an index for the hashed result, then we hope that the smaller the column, the better, in order to save data storage space. Especially when creating an index in the database, the indexed fields are naturally as small as possible. 4. To be even, especially when there are multiple nodes, it is more important to ensure that each key is evenly distributed, otherwise the load cannot be balanced 5 When .rehash, make sure that the redistribution of keys is as small as possible to avoid causing a big impact on the backend. Common hash functions such as md5, sha-1, crc16, crc32, etc.