[ Written in front ] In fact, the exam has passed for several days, and the answers and test questions for the soft exam network administrator in May 2023 have not been released online. It is estimated that it will be July, and there may not be many people who are beginners. Next, I will share with you
the knowledge points related to the error-prone knowledge points of the 10-year real questions that I have sorted out: common knowledge points of network administrators in the soft test, error-prone knowledge points, a collection of wrong questions collected from real questions over the years, a summary of all switches’ commands, soft test Review guide, soft exam must memorize knowledge points.
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Table of contents
1. Frequently Asked Questions Collection
1. The storage path of DHCP is etc/dhcpd.cong
2. When the direct transfer instruction is executed, the instruction address is sent to the program counter
3. The main function of setting 'cache' between the CPU and the main memory is to solve the speed mismatch between the CPU and the main memory Question
4. The multiplexing method used by the El carrier is time division multiplexing, and the data rate provided is 2048 kb/s
5. In the process of IPV6 stateless auto-configuration, the host appends the MAC address to the address prefix to generate a link-local address .
6. The routing update cycle of the default protocol of RIP is 30S , and the holding time is 180S.
7. VLANs are divided in the local area network, and different groups must communicate with each other through trunk ports, and the data frames between each VLAN must be marked with different VLAN tags .
8.DHCP working process
初次启动采用DhcpDiscover申请IP地址
采用DhcpOffer 报文提供给客户机的IP地址、DNS、DHCP服务器地址、默认网关地址。
用户决定采用则发送DhcpRequest报文请求租用
DHCP采用DhcpAck报文确认后客户机就可以使用
9. Enter ftp://ftb.abc.com in the browser address bar to access the FTP site ftp.abc.com
10. To know whether a host can log in remotely, you can use port scanning to check
11. The value of VLAND The range is 1~4094 . Among them, the VLAN with ID 1 is the default VLAN of the system, which is usually used for network device management. VLAN 1 is not allowed to be deleted
. 12. The domain name cannot be accessed, but the IP can be accessed mainly because the DNS cannot be resolved . The core reason is that the computer and the DNS server are not present. The same subnet
13.route print is to display the local network routing information under the wondows system, but the linux system is netstat-nr
Ipconfig is to configure the network port and information under the windows system, but the linux system is ifconfig
14.In the SNMP protocol, management The protocol and default port number used by the station to receive the Trap message sent by the agent is UDP 92
Management process port number: 92 ---- Receive Trap message ;
Agent process port number: 91 ---- Receive get /set message ;
15. The communication mechanism between management stations is added for the first time in SNMP V2, which is a necessary feature of distributed network management. For this reason, notification messages and management station database (manager-to-manager MIB)
2. Switch command set
16. Common knowledge points of switch commands
Normal mode: switch>
Privileged mode: switch#
Global mode: switch(config)#Interface mode
: switch(config-if)#line mode
: switch(config-line)#vlan
mode: switch( vlan)#Mode
conversion command:
normal mode --------> privileged mode: enable
privileged mode ---------> normal mode exit
privileged mode --------> global mode : config iterminal
global mode --------> privileged mode exit/end/ctrl+z
global mode --------> interface mode: interface fastEthernet 0/1
interface mode ------ -->global mode exit
global mode------->line mode: line console 0 / line vty 0 4
line mode------->global mode exit
Line mode------ -->Privileged mode: end/ctrl+z
privileged mode------->VLAN mode: vlan database
Other common commands:
Leave privileged mode: switch# disable
Save configuration information: Switch# write
Restart the switch: switch# reload
Set the hostname: switch(config)# hostname name
Enter the console: switch(config)#line console 0
Enter the virtual terminal: switch(config)# line vty 0 4
Set the IP: switch(config)# ip address
Set the domain name: switch (config)# ip domain-name
set domain name server: switch(config)# ip name-server
set default gateway: switch(config)# ip default-geteway
set encrypted password: switch(config)# enable secret xxx
set non-secret password : switch(config)# enable password xxx
view flash memory: switch# dir flash
idle timeout setting: switch(config-line)#exec-timeout 3 0
The difference between End and exit
End is to return to the privileged mode directly, and exit means to return to the previous layer
However, Huawei will be used in the network administration exam in 2018, so you can pay more attention
17. Windows Server 2003 needs to install DNS service
specially . 18. 169.254.XX is the IP address automatically assigned to the client by Windows operating system when the DHCP information lease fails. The possible reason for the failure is that the DHCP server is not working. 19.
Ipconfig
/all显示所有适配器的完整TCP/IP配置信息；
/registerdns初始化计算机上配置的DNS名称和IP地址的手工动态注册
/flushdns清理并重设DNS客户解析器缓存的内容；
/displaydns显示DNS客户解析器缓存的内容，包括从本地主机文件预装载的记录
20. X.509 is a digital certificate standard formulated by the International Telecommunication Union (ITU-T). The format of the digital certificate follows the X.509 standard.
21. The digital signature uses the private key of the sender to encrypt the digest of the message; Encrypted is the session key.
22. When the client requests to execute an html type file, the server does not execute the file and directly passes it to the browser
. Send control information
24. Static allocation of VLAN: specify the VLAN to which each port of the switch belongs;
Dynamic allocation of VLAN: VLAN can be divided according to MAC address, network layer protocol, network layer address, IP broadcast domain or management strategy;
25. Address 0.0 .0.0 means the local address, which can only be used as the source address, and cannot be used as the destination address.
The address 127.0.0.1 means the local loop address, which is usually used as the destination address to test the local TCP/IP
loop Stateful interior gateway protocol;
27.IP is a network layer connectionless protocol;
SNMP是简单网络管理协议，属于应用层；
SMTP是简单邮件传输协议，也是应用层协议；
TCP is a transport layer protocol.
28. Manchester coding from high to low means 1, low to high means 0; as long as the differential Manchester coding changes, it means 1, and if it does not change, it means 0. 29. Portability is not
a necessary feature of the algorithm;
30. The average of the hard disk Access time = average seek time + average waiting time
31. Move the cursor to the left blank space at the beginning of the text line and click the left button of the mouse to select a line
32. The transport layer protocol used by the DNS service is UDP
33. The trap message is sent by the agent to the management station without a response
34. In the Windows operating system, FTP is a component that has nothing to do with Web access
35. The main purpose of the NAT function of the firewall is Hide the internal network IP address and topology information.
36. ARP attack is only aimed at the local area network. It can purposely issue wrong ARP broadcast packets, and hackers can use it to steal network data.
37. The protocol used to receive emails is POP3
. 38. Put the physical network The benefits of dividing into VLANs are:
① control network traffic ② improve network security ③ flexible network management
39. HDLC protocol (High Level Data Link Control) is a bit-oriented synchronous link control protocol
41. Due to the blocking function of the router, this broadcast frame will not pass the router to the right subnet. 42.
There are three types of IPv6 addresses: unicast, multicast, and anycast
单播（Unicast）：单个网络接口的标识符，用于作为目标地址把分组转发到特定的结点；
组播（multicast）：一组接口的标识符，发往组播地址的分组被传送给该地址标识的所有接口;
任意播（anycast）：一组网络接口的标识符。发往任意播地址的分组被传送给该地址标识的接口之一，通常是离路由最近的接口。这种地址不能用作源地址，而只能作为目标地址，并且只能指定给IPv6路由器;
43. The hardware address is the service access point of the data link layer.
44. Ports 21, 23 and 25 are the port numbers assigned to FTP, Telnet and SMTP
by default. DNS is port 53. 45. Channel transmission rate comparison 4 E1 = E2 ;4 E2 = E3 ;4 E3 = E4 ;4 E4 = E5 ;
E1 channel transmission speed is 2.048Mb/s each sub-channel 64kb/s
E2 channel transmission speed is 8.448Mb/s E3 channel transmission speed is 34.368Mb/s
E4 channel transmission The speed is 139.264Mb/s E5 channel transmission rate is 565.148Mb/s
46.Windows disk defragmentation program (can make each file and folder occupy continuous space on the disk, and merge the available space on the disk), through the disk Defragmentation, (can improve access efficiency to files and folders)
47. Data flow diagram for architecture design and interface design;
48. Objects protected by software copyright do not include algorithms
49. T1, E1 carrier standards are all using synchronous time division Multiplexing technology, T1 dedicated telephone connection; wavelength division multiplexing technology is used in optical fiber communication, and different sub-channels are carried by light waves of different wavelengths
. Repeater and bridge mainly play the role of filtering frames.
51. ICMP messages are encapsulated in (ip) protocol data units for transmission. If the TTL field is found to be zero during the transmission of IP datagrams, the router will send (timeout) messages
53.Console port – special cable connected to the serial port of the computer
Twisted pair (RJ-45) port – connected to the Ethernet
fiber port through a twisted pair – can provide gigabit data transfer rate, usually used to connect to the server Fiber-optic network card
GBIC port - the GBIC slot of the switch is used to install the Gigabit port converter
Ethernet port - to connect the Ethernet card.
54. List items are guided by dt
55. Use align to set its horizontal alignment position; use valign attribute to set the vertical alignment position of text ;
56. In the built-in object of ASP, the ( response ) object can modify the value in the cookie
57.80 port Port 21 and 20 are used
as control and data ports of the file transfer protocol,
port 23 is the listening port of the Telnet server, and
port 25 is the service port of SMTP for mail transmission.
Ports greater than 1024 are usually port 58 used by the service request client.
Sending a message with a digital signature has the following four steps: generating a message, generating a summary of the message, signing the summary and sending the message
3. Collection of wrong questions in the past 3 years
1. CPU access to main memory (RAM) is random access . The main memory and cache address conversion work in the CUP is automatically completed by hardware
2. MPEG (Moving picture experts group) is aimed at the moving picture experts group
3. Differential Manchester encoding and Manchester encoding both have their own synchronization information
4. Workspace subsystem-level District Subsystem-Vertical Trunk Subsystem-Building Group Subsystem
5. What causes signal transmission loss along the link is the attenuation value
6. Ping is an application of ICMP , and UDP is unreliable transmission .
7. Cookies store user ID, password, mobile phone number and other citizen information
8. Remote assistance software is based on TCP
9. The command to display an access control list on a specific interface is display acl access-list-number
10. How to distinguish the source from the target
11.Pop3 interface is TCP110 , STMP is TCP25
12.The protocol used by ftp.ccc.com is http
13.Data bus width—binary digits
14. DRAM dynamic random access memory, which needs to be refreshed regularly, uses capacitor storage; SRAM static random access memory
15. Three elements of data model: data structure (static), data operation (dynamic), integrity constraints
16. ADSL in PSTN (public telephone network ) The network implements multiple sub-channels through Frequency Division Multiplexing (FDM), one part is used for uploading and the other part is used for downloading. 17. The router forwards based
on the destination IP address . .IPV4 header length is 20 bytes, IPV6 header length is 40 bytes 20. The fields of ACK and SYN indicate the meaning Synchronization flag, when SYN is 1, it means a connection request or connection acceptance. ACK: The length of this field is 1 bit. Confirmation flag, when ACK is 1, it indicates that the confirmation number field is valid, and at the same time it is 1, indicating that the connection is opened passively and established. 21. The minimum frame length required in Ethernet is 64 bytes. This value is determined by the working speed of Ethernet and the maximum network segment length. The goal is to ensure the normal operation of the CSMA/CD protocol. The minimum frame length is based on the detection of conflicts in the network the longest time. 22. Outlook is an email client , and webmail is a browser. 23. The application-level gateway firewall is the isolation point of the internal and external networks, which can monitor and filter the communication data flow of the application layer.
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The well-prepared test guide, I hope it can bring you help, let's pass it together! ! !
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