Summary of 100 knowledge points that Linux operation and maintenance & network engineers should know!

#1) What is a link?

A link refers to the connection between two devices. It includes the cable types and protocols used for one device to communicate with another device.

2) What are the layers of the OSI reference model?

There are 7 OSI layers: physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer.

3) What is a backbone network?

Backbone networks are centralized infrastructure designed to distribute different routes and data to various networks. It also handles bandwidth management and various channels.

4) What is LAN?

LAN is the abbreviation of Local Area Network. It refers to the connection between a computer and other network devices located in a small physical location.

5) What is a node?

Node refers to the point where the connection occurs. It can be a computer or device that is part of a network. In order to form a network connection, two or more nodes are required.

6) What is a router?

Routers can connect two or more network segments. These are smart network devices that store information in their routing tables, such as paths, hop counts, etc. With this information, they can determine the best path for data transfer. Routers operate at the OSI network layer.

7) What is a point-to-point link?

It refers to a direct connection between two computers on the network. A point-to-point connection does not require any other network equipment other than connecting cables to the two computers' NIC cards.

8) What is anonymous FTP?

Anonymous FTP is a way of granting users access to files in a public server. Users allowed to access data in these servers do not need to identify themselves but log in as anonymous guests.

9) What is a subnet mask?

The subnet mask is combined with the IP address to identify two parts: the extended network address and the host address. Like an IP address, a subnet mask consists of 32 bits.

10) What is the maximum length allowed for a UTP cable?

A single segment of UTP cable has an allowed length of 90 to 100 meters. This limitation can be overcome by using repeaters and switches

11) What is data encapsulation?

Data encapsulation is the process of breaking down information into smaller manageable chunks before transmitting it over a network. In this process, source and destination addresses are appended to the header along with parity.

12) Describe network topology

Network topology refers to the layout of a computer network. It shows the physical layout of the devices and cables, and how they connect to each other.

14) Briefly describe NAT.

NAT is Network Address Translation. This is a protocol that provides a way for multiple computers on a public network to share a single connection to the Internet.

15) What is the work of the network layer under the OSI reference model?

The network layer is responsible for data routing, packet switching and network congestion control. Routers operate under this layer.

16) How does network topology affect your decisions when setting up your network?

Network topology determines what media must be used to interconnect devices. It also serves as the basis for materials, connectors and terminals suitable for the setup.

17) What is RIP?

RIP, short for Routing Information Protocol, is used by routers to send data from one network to another.

It efficiently manages routing data by broadcasting its routing table to all other routers in the network. It determines network distance in hops.

18) What are the different ways to protect computer networks?

There are several ways to do this. Install reliable and updated antivirus programs on all computers. Make sure the firewall is set up and configured correctly. User authentication will also be of great help. All these combined will form a highly secure network.

19) What is NIC?

NIC is the abbreviation of network interface card (network interface card). This is connected to the PC to connect to the network Shenbei. Each NIC has its own MAC address, which identifies the PC on the network.

20) What is WAN?

WAN stands for Wide Area Network. It is the interconnection of geographically dispersed computers and devices. It connects networks located in different regions and countries.

21) What is the importance of OSI physical layer?

The physical layer performs the conversion from data bits to electrical signals and vice versa. This is a consideration and setup for network equipment and cable types.

22) How many layers are there under TCP/IP?

There are four layers: network layer, Internet layer, transport layer and application layer.

23) What are proxy servers and how do they protect computer networks?

Proxy servers mainly prevent external users from identifying the IP address of the internal network. Not knowing the correct IP address or even identifying the physical location of the network. Proxy servers can make a network virtually invisible to outside users.

24) What is the function of the OSI session layer?

This layer provides protocols and methods for two devices on the network to communicate with each other by holding sessions. This includes setting up the session, managing the exchange of information during the session, and the dismissal process when the session is terminated.

25) What is the importance of implementing a fault tolerant system? Limited?

Fault-tolerant system ensures continuous data availability. This is achieved by eliminating single points of failure. However, there are certain situations where this type of system will fail to protect data, such as accidental deletion.

26) What does 10Base-T mean?

10 refers to the data transfer rate, in this case 10Mbps. "Base" refers to baseband. T stands for twisted pair, which is the cable used for this network.

27) What is a private IP address?

Private IP addresses are assigned for intranet use. These addresses are used on the internal network and cannot be routed on the external public network. These ensure that there are no conflicts between internal networks, while ranges of private IP addresses are also reusable across multiple internal networks since they do not "see" each other.

28) What is NOS?

NOS or Network Operating System is specialized software whose main task is to provide a network connection to a computer so that it can communicate with other computers and connected devices.

29) What is DoS?

DoS or Denial of Service attack is an attempt to prevent a user from accessing the Internet or any other network service. This attack may take different forms, consisting of a group of permanents. A common way to do this is to overload the system's servers so that they can no longer handle legitimate traffic and will be forced to reset.

30) What is OSI and what role does it play in computer networking?

OSI (Open Systems Interconnection) serves as the reference model for data communications. It consists of 7 layers, each of which defines a specific aspect of how network devices connect and communicate with each other. One layer handles the physical media used, while the other layer dictates how the data is actually transferred over the network. In addition, when searching for public accounts, Linux should learn how to reply "monkey" in the background and get a surprise gift package.

31) What is the purpose of a cable being shielded and having twisted pairs?

The main purpose is to prevent crosstalk. Crosstalk is electromagnetic interference, or noise, that can affect data transmitted over cables.

32) What are the advantages of address sharing?

Address sharing provides inherent security advantages by using address translation instead of routing. This is because hosts on the Internet can only see the public IP address of the external interface on the computer that provides address translation, not the private IP address on the internal network.

33) What is a MAC address?

MAC, or Media Access Control, uniquely identifies a device on a network. It is also known as physical address or Ethernet address. The MAC address consists of 6 bytes.

34) In terms of the OSI reference model, what is the equivalent layer or layers of the TCP/IP application layer?

The TCP/IP application layer actually has three peers on the OSI model: session layer, presentation layer and application layer.

35) How to identify the IP class of a given IP address?

By looking at the first octet of any given IP address, you can identify whether it is Class A, Class B, or Class C. If the first octet starts with bit 0, the address is Class A. If it starts with bit 10, the address is Class B. If you start with 110, then it is a Class C network.

36) What is the main purpose of OSPF?

OSPF, or Open Shortest Path First, is a link-state routing protocol that uses routing tables to determine the best path for data exchange.

37) What is a firewall?

Firewalls are used to protect internal networks from external attacks. These external threats could be hackers who want to steal data or computer viruses that can eliminate data instantly. It also prevents other users from external networks from accessing the private network.

38)Describe star topology

A star topology consists of a central hub connected to the nodes. It's one of the easiest to set up and maintain.

39) What is a gateway?

A gateway provides a connection between two or more network segments. It is usually a computer that runs the gateway software and provides translation services. This translation is key to allowing different systems to communicate on the network.

40) What are the disadvantages of star topology?

One major disadvantage of a star topology is that once the central hub or switch is damaged, the entire network becomes unavailable.

41) What is SLIP?

SLIP or Serial Line Interface Protocol is actually an older protocol developed in the early days of UNIX. This is one of the protocols used for remote access.

42) Give some examples of private network addresses.

10.0.0.0, the subnet mask is 255.0.0.0

##172.16.0.0, the subnet mask is 255.240.0.0

192.168.0.0, subnet mask is 255.255.0.0

43) What is tracert?

Tracert is a Windows utility that can be used to trace the route of data collection from a router to a target network. It also shows the number of hops taken during the entire transmission route.

44) What are the functions of a network administrator?

Network administrators have many responsibilities that can be summarized into 3 key functions: installing the network, configuring network settings, and maintaining/troubleshooting the network.

45) Describe a disadvantage of peer-to-peer networks.

When you are accessing resources shared by a workstation on the network, the performance of that workstation is reduced.

46) What is a hybrid network?

Hybrid networking is a network setup that utilizes client-server and peer-to-peer architecture.

47) What is DHCP?

DHCP is the abbreviation of Dynamic Host Configuration Protocol. Its main task is to automatically assign IP addresses to devices on the network. It first checks the next available address that is not already occupied by any device and then assigns it to the network device.

48) What is the main job of ARP?

The main task of ARP or Address Resolution Protocol is to map known IP addresses to MAC layer addresses.

49) What is TCP/IP?

TCP/IP is the abbreviation for Transmission Control Protocol/Internet Protocol. This is a set of protocol layers designed to exchange data over different types of computer networks, also known as heterogeneous networks.

50) How to use a router to manage the network?

The router has a built-in console that allows you to configure different settings such as security and data logging. You can assign restrictions to your computer, such as the resources it is allowed to access, or a specific time of day when you can browse the Internet.

You can even impose restrictions on sites that are not visible across the entire network.

51) What protocol can be applied when you want to transfer files between different platforms like UNIX system and Windows server?

Use FTP (File Transfer Protocol) to transfer files between these different servers. This is possible because FTP is platform independent.

52) What is the use of default gateway?

The default gateway provides a way for the local network to connect to the external network. The default gateway for connecting to external networks is usually the address of the external router port.

53) One way to protect your network is to use passwords. What is considered a good password?

A good password consists not only of letters but also a combination of letters and numbers. Passwords that combine uppercase and lowercase letters are more advantageous than passwords that use all uppercase letters or all lowercase letters. The password must not be easily guessed by hackers, such as date, name, favorites, etc.

54) What is the correct termination rate for UTP cables?

Normal termination for unshielded twisted pair network cable is 100 ohms.

55) What is netstat?

Netstat is a command line utility. It provides useful information about the current TCP/IP settings of the connection.

56) What is the number of network IDs in a Class C network?

For Class C networks, the number of available network ID digits is 21. The number of possible network IDs is 2, increasing to 21 or 2,097,152. The number of host IDs per network ID is 2, increasing to 8 minus 2, or 254.

57) What happens when using a cable longer than the specified length?

Cables that are too long can cause signal loss. This means that data transmission and reception will be affected because the signal length is reduced.

58) What common software issues can cause network defects?

Software related issues can be any one or combination of the following:

- Client Server Issues

- Application conflict

- Configuration error

- Protocol mismatch

- Security Issues

- User Policy and Rights Issues

59) What is ICMP?

ICMP is the Internet Control Message Protocol. It provides messaging and communication for protocols within the TCP/IP protocol stack. This is also the protocol that manages error messages used by network tools such as PING.

60) What is Ping?

Ping is a utility that allows you to check connections between network devices on your network. You can ping a device using its IP address or the device name (such as computer name).

61) What is peer-to-peer (P2P)?

A peer is a network that does not reply on the server. All PCs on the network are individual workstations.

62) What is DNS?

DNS is the Domain Name System. The main function of this network service is to provide host names for TCP/IP address resolution.

63) What are the advantages of optical fiber over other media?

A major advantage of fiber optics is that they are less susceptible to electrical interference. It also supports higher bandwidth, meaning more data can be sent and received. There is also very little signal degradation over long distances.

64) What is the difference between a hub and a switch?

The hub acts as a multi-port repeater. However, as more and more devices are connected to it, it will not be able to effectively manage the traffic passing through it. Switches offer a better alternative that can improve performance, especially when high traffic is expected on all ports.

65) What are the different network protocols supported by Windows RRAS service?

Supports three major network protocols: NetBEUI, TCP/IP and IPX.

66) What are the largest networks and hosts in Class A, B and C networks?

For Class A, there are 126 possible networks and 16,777,214 hosts

For Class B, there are 16,384 possible networks and 65,534 hosts

For class C, there are 2,097,152 possible networks and 254 hosts

67) What is the standard color sequence for straight-through cables?

Orange/white, orange, green/white, blue, blue/white, green, brown/white, brown.

68) What protocols fall below the application layer of the TCP/IP protocol stack?

The following are TCP/IP application layer protocols: FTP, TFTP, Telnet and SMTP.

69) You need to connect two computers for file sharing. Is it possible to do this without using a hub or router?

Yes, you can connect two computers together using a cable. A crossover cable can be used in this case. In this setup, the data transmit pin of one cable is connected to the data receive pin of the other cable and vice versa.

70) What is ipconfig?

Ipconfig is a utility often used to identify the address information of computers on a network. It can display the physical address as well as the IP address.

71) What is the difference between straight-through and crossover cables?

Straight-through cables are used to connect your computer to a switch, hub, or router. A crossover cable is used to connect two similar devices together, such as PC to PC or hub to hub.

72) What is client/server?

Client/server is a type of network in which one or more computers act as servers. The server provides a centralized repository of resources such as printers and files. Clients are workstations that access the server.

73) Describe the network.

Network refers to the interconnection between computers and peripheral devices used for data communication. Network connections can be made using a wired cable or via a wireless link.

74) When moving a NIC card from one PC to another, is the MAC address also transferred?

Yes, that's because the MAC address is hardwired to the NIC circuit, not the PC. This also means that the PC can have a different MAC address when the NIC card is replaced by another one.

75) Explain clustering support

Cluster support refers to the ability of a network operating system to connect multiple servers in a fault-tolerant group. The main purpose of this is that in the event of one server failure, the next server in the cluster will continue all processing.

76) In a network containing two servers and twenty workstations, where is the best place to install an antivirus program?

Antivirus programs must be installed on all servers and workstations to ensure protection. This is because individual users can access any workstation and introduce computer viruses when plugging in a removable hard drive or flash drive.

77) Describe Ethernet.

Ethernet is one of the popular networking technologies used today. It was developed in the early 1970s and is based on specifications laid out in the IEEE. Ethernet is used in local area networks.

78) What are the disadvantages of implementing a ring topology?

If one workstation on the network fails, the entire network may be lost. Another disadvantage is that when adjustments and reconfigurations need to be made in specific parts of the network, the entire network must also be temporarily shut down. In addition, when searching for public accounts, Linux should learn how to reply "monkey" in the background and get a surprise gift package.

79) What is the difference between CSMA/CD and CSMA/CA?

CSMA/CD or collision detection, resend data frames whenever a collision occurs. CSMA/CA, or Collision Avoidance, will first broadcast the intent before data is transmitted.

80) What is SMTP?

SMTP is the abbreviation of Simple Mail Transfer Protocol. This protocol handles all internal mail and provides the necessary mail delivery services over the TCP/IP protocol stack.

81) What is multicast routing?

Multicast routing is a form of targeted broadcast that sends a message to a selected group of users rather than sending it to all users on a subnet.

82) What is the importance of encryption on the Internet?

Encryption is the process of converting information into a code that is unreadable by the user. It is then translated or decrypted back to its normal readable format using a secret key or cipher. Encryption helps ensure that information intercepted midway remains unreadable because the user must have the correct password or key.

83) How to arrange and display IP addresses?

An IP address appears as a series of four decimal numbers separated by periods or dots. Another term for this arrangement is dotted decimal format. An example is 192.168.101.2

84) Explain the importance of authentication.

Authentication is the process of verifying user credentials before they log into a network. It is usually done using a username and password. This provides a secure means of limiting access from harmful intruders on your network.

85) What does tunnel mode mean?

This is a data exchange mode in which two communicating computers do not use IPSec themselves. Instead, the gateway that connects the LAN to the transit network creates a virtual tunnel that uses the IPSec protocol to secure all traffic passing through it.

86) What are the different technologies involved in establishing a WAN link?

Analog connection - uses regular phone lines; Digital connection - uses digital phone lines; Switched connection - uses sets of links between the sender and receiver to move data.

87) What is one advantage of grid topology?

In the event one link fails, there is always another link available. Mesh topology is actually one of the most fault-tolerant network topologies.

88) What common hardware-related issues may occur when troubleshooting computer network problems?

Most networks are made up of hardware. Problems in these areas may include hard drive failure, corrupted NIC or even hardware boot. Incorrect hardware configuration is also one of the problems.

89) What can be done to fix the signal degradation problem?

A common way to deal with this problem is to use repeaters and hubs as it will help regenerate the signal, thus preventing signal loss. Checking that the cable is properly terminated is also a must.

90) How does the Dynamic Host Configuration Protocol assist network management?

Instead of visiting each client computer to configure a static IP address, network administrators can apply the Dynamic Host Configuration Protocol to create a range of IP addresses called ranges that can be dynamically assigned to clients. pool.

91) Explain the overview of network concepts?

Profiles are configuration settings set for each user. For example, you can create profiles that place users into groups.

92) What is Sneakernet?

Sneakernet is considered the earliest form of networking, in which removable media (such as disks, tapes) were used to physically transfer data.

93) What is the role of IEEE in computer networks?

The IEEE or Institute of Electrical and Electronics Engineers is an organization of engineers that publishes and manages standards for electrical and electronic equipment. This includes network devices, network interfaces, cablings and connectors.

94) What protocols are under the Internet layer of TCP/IP?

There are 4 protocols managed by this layer. These are ICMP, IGMP, IP and ARP.

95) Speaking of networking, what are permissions?

Permission refers to the authorization to perform specific operations on the network. Each user on the network can be assigned individual permissions, depending on what that user must allow.

96) What is a basic requirement for establishing a VLAN?

A VLAN is required because there is only one broadcast domain at the switch level, which means that every time a new user connects, the information is propagated throughout the network. VLANs on switches help create separate broadcast domains at the switch level. It is used for security purposes.

97) What is IPv6?

IPv6 or Internet Protocol version 6 was developed to replace IPv4. Currently, IPv4 is being used to control Internet traffic, but IPv4 is already saturated. IPv6 is able to overcome this limitation.

98) What is the RSA algorithm?

RSA is the abbreviation of Rivest-Shamir-Adleman algorithm. It is currently the most commonly used public key encryption algorithm.

99) What is mesh topology?

A mesh topology is a setup in which every device is directly connected to every other device on the network. Therefore, it requires each device to have at least two network connections.

100) What is the maximum segment length for a 100Base-FX network?

The maximum allowed length of a network segment using 100Base-FX is 412 meters. The maximum length of the entire network is 5 km.