Sian O & M engineer interview questions

Sian O & M engineer interview questions

1. What are the functions of the following Linux commands?

Init 0

Chkconfig -- level 3 sendmail on

Tar-czvf test.tar.gz ./

Chown-R www: www/usr/local/apache/htdocs/

Ln-s/data2/log/var/log/sina_log/

[-D/data1/logs] & mv/data1/logs/data1/logs. old

Rsync 192.168.0.200: software.tar.gz.

Umount/data0

Rpm-ivh sina. rpm

Rpm-qf/bin/ls

2. What software does a Linux Server need to install for HTTP, DNS, database, HTTP proxy, virtual machine, and Server Load balancer?

3. Which command can be used to back up a database in Mysql?

4. What is the role of ARP?

5. What is the TCP three-way handshake process?

6. How to enter the single-user mode in Linux?

7. If you are a Linux system administrator, You need to execute the following command on the 500 servers in as short as possible:
Sysctl-w-q net. ipv4.tcp _ tw_reuse = 1

What are your solutions?

8. List the transport layer port numbers and application layer protocols of the following services.

A. netbios: 137/138/139

B. telnet: 23

C. ftp: 21

D. http: 80

E. dns: 53

F. https: 443

E. Terminal services: 3389

G. SMTP: 25

H. rsyncd: 873

9. Currently, users with IP addresses 192.168.1.10 always maliciously connect to port 80 of A Linux server. What kind of countermeasures do you have as a system administrator? (It is best to write out detailed commands or steps)

10. What is KeepAlive In the httpd. conf file? What are its advantages and disadvantages?

It is easy to determine whether or not we want to enable KeepAlive, that is, whether a user's page request will send multiple HTTP requests to the server. 1. if only one request on each page is dynamically generated, and 180 (four of them may not be, but not important) are static, which of the following methods should be used to separate static and dynamic data on two servers ). Disable the dynamic application KeepLive and open the static server KeepLive.
2. layer-4 switching or layer-7 switching or cache servers are deployed before the front-end. This will enable system expansion and enable the server's KeepLive to be opened with better results.
3. We should consider optimizing their apache. I heard that a process occupies up to xxM of memory, which is terrible. It is normal to say within 10 m, but this is an option.

11. What is the difference between inted mode and stand-alone mode in FTP server? What is the difference between Pasv and Port modes in transmission mode?

The Pasv passive mode client sends a connection request to the FTP port of the server (21 by default). The server accepts the connection and establishes a command link. When data needs to be transmitted, the client sends a connection request to the idle port of the server and establishes a data link to transmit data.

The client sends a connection request to the FTP Port (21 by default) of the server. The server accepts the connection and establishes a command link. When data needs to be transmitted, the server sends a connection request from Port 20 to the idle port of the client and establishes a data link to transmit data.

12. What layer does Server Load balancer belong to in the OSI of TCP/IP? What is the main role of this layer of responsibility?

Layer 4Provides end-to-end Interfaces

13. (single answer) which of the following statements about FTP and TFTP is true? (D)

(A) Both FTP and TFTP are based on the TCP protocol (B). Both FTP and TFTP are based on the UDP protocol.

(C) Both FTP and TFTP are based on UDP protocol (D) FTP is based on TCP protocol, and TFTP is based on UDP protocol

Ii. Shell:

1. Assume that a web server accesses the LOG with the following line:

61.159.245.95--[01/Aug/2003: 15: 39: 39 + 0800] "GET/epl.shtml HTTP/1.1" 302 251 "http://www.hao123.com/sport2/football.htm" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98; Avant Browser [avantbrowser.com])"

The LOG file contains more than 0.1 million rows. If the top 10 IP addresses requested in the last 0.1 million rows are listed, the following result is displayed:

119 211.101.169.200

103 211.101.169.206

50 61.149.38.249

47 219.234.217.100

23 211.136.72.123

15 218.106.178.2

15 211.162.238.236

11 202.106.138.194

Please use a line of command to display the above results

Tail-n 100000 log | awk '{print $1} | sort | uniq-C | sort-rn | head-10'

2. Run a line of command to find the file whose content contains sina and whose name ends with. config.

Find.-name "*. config" | xargs grep-E "sina"

Iii. database:

1. The following student information table is available:

Table Name (Student)

Field Name Description

ID: Student ID

Name

Birth date

Sex Name

Description

Write SQL to count boys

2. (multiple answers) What storage engine in mysql supports transactions? ()

(A) Innodb (B) NDB Cluter (C) MyISAM (D) BLACKHOLE (E) FEDERATED

3. (multiple choice) The command used to view the structure of a table in Mysql is ()

(A) desc table_name (B) explain table_name

(C) show table status like 'table _ name' (D) show create table table_name

4. What is the purpose of Mysql Query_cache? How does it work?

4. Storage knowledge

1. Describe how Raid0, Raid1, Raid0 + 1, and Riad5 work. What are their advantages and disadvantages and where are they suitable?

Raid 0 continuously splits data and reads and writes data to multiple disks in parallel with a high data transmission rate

Raid 1 image utilization rate: 50%, high security factor

Raid 0 + 1A combination of RAID 0 and RAID 1, also known as RAID 10

Raid 5 stores data and the corresponding parity information on each disk that makes up Raid 5. When one disk of Raid 5 is damaged, use the remaining data and the corresponding parity information to restore the damaged data

2. Do you know about SAN and NAS? What are their differences and what are the products of their respective applicable services?

SAN: Storage Area Network

SAN is composed of RAID arrays connected to fiber channels. SAN communicates with servers and clients through SCSI commands instead of TCP/IP. Data Processing is block level ).

NAS Network Attached StorageNetwork attached storage

The typical component is to use the TCP/IP protocol

The volume file server, which processes data at the file level ).

You can append the NAS storage device to an existing shard.

The easiest way to distinguish SAN from NAS is to think about how the two are technically implemented. In SAN multi-deployment and e-commerce applications, a large amount of data backup and other services need to be stored and transmitted frequently on the Internet;

SAN can unload a large amount of data traffic from your primary network, freeing your Ethernet from data congestion.

NAS is usually a server group application server, mail server, and so on. storage devices are easily attached to this system.