Some necessary problems of computer network in Linux system

Day

1. What is the role of IP address? IP address classification?

The role of an IP address: The network address used to identify a node.

IP Address Classification: class A 1-127

Class B 128-191

Class C 192-223

2. What is the subnet mask? Default A B class C subnet mask?

The role of the subnet mask: The network bit and the host bit used to identify the IP address.

Class A: 255.0.0.0

Class B: 255.255.0.0

Class C: 255.255.255.0

3. What is the role of the gateway?

The gateway's role: from one network to another.

4. What is the role of public and private addresses and the scope of private addresses?

Public Address: Public address can also be called a public address, through which he can directly access the Internet, he is in the WAN category

Of

The function of private address: Private address can also be called a special network address, specifically for the internal use of the organization, he is within the scope of the LAN,

Out of the local area network is unable to access the Internet.

Range of private addresses:

A: Class 10.0.0.1-10.255.255.254

B: Class 172.16.0.1-172.31.255.254

C: Class 192.168.0.1-192.168.255.254

5. How to view the Windows host IP address with a command, how to view the Windows host MAC address with a command?

Start-command prompt-run ipconfig

View IP in Linux: Run Ifconfig directly

View MAC Address: Start-command prompt-run ipconfig/all.

Day 02

1. What is the function of the computer network?

Function of network: Data communication resource sharing increases reliability and improves system processing ability

2. Conversion of computer storage units?

Computer storage can be measured in bits and bytes

8 Guests

1 bytes

1024 byte 1KB

1024KB 1MB

1024MB 1GB

1024GB 1TB

1024TB 1PB

1024PB 1EB

3. How many layers does the OSI reference Model have? name and function of each layer?

OSI Reference Model A total of seven layers from bottom to top are physical layers-data Link layer-network layer-Transport Layer-session Layer-presentation layer-should

Use layer

The meaning of each layer:

Physical layer: Establishes, maintains, disconnects the physical connection, defines the interface and the medium, realizes the transmission of the bit stream.

Data Link layer: the establishment of logical links, hardware address addressing, error checking and other functions, through the MAC address to achieve data communication,

Frame wrapping, frame transfer, frame synchronization. The switch works at the data link layer.

Network layer: Logical address addressing, the realization of communication between different networks, the definition of IP address, for data transmission selection of the best path

The router works at the network layer.

Transport Layer: Defines the protocol port number of the transmitted data, as well as the flow control and error checking, realizes the interconnection between program and program, reliable and not

Reliable transmission.

Session Layer: Establish, manage, abort sessions, such as breakpoint continuation.

Presentation layer: The representation of data, such as encryption, compression.

Application layer: An excuse for Web services and end users

4. Four-layer data unit under OSI Seven-layer Reference Model

Transport Layer Segment segment

Network Layer Pack Packet

Data Link Layer Frames frame

Physical Layer

5.

Bit bit

What are the layers of the TCP/IP protocol? What's the name?

The TCP/IP protocol consists of five layers or four layers:

TCP/IP layer four

Network interface Layer

Network layer

Transport Layer

Application Layer

TCP/IP layer Five

Physical Layer

Data Link Layer

Network layer

Transport Layer

Application Layer

6. Application, transmission, Network layer protocol?

Application layer: Http,https,ftp,tftp,smtp,pop3,snmp,dns,telnet

Transport Layer: TCP,UDP

Network layer: Icmp,igmp,ip,arp,rarp

7. TCP/IP five layers per layer of equipment

Application-tier computers

Transport Layer Firewall

Network layer Routers

Data Link Layer Switches

Physical Layer

Card

Day 03

1. What is the order of t568a and t568b? which is responsible for sending, and which is responsible for receiving?

T568A line sequence: White green, green, white orange, blue, white blue, orange, white brown, brown

T568B line sequence: white orange, orange, white green, blue, white blue, green, white brown, brown

Send, 3,6 receive

2. What is a standard cable? What is a crossover cable? What are the conditions for use?

Standard cable (direct or straight line): For connecting different devices (A-a,b-b)

Crossover cable: For connecting the same device (A-B)

Day 04

1. What is the length of MAC address? How many bytes?

MAC address length 48 bits (6 bytes), the first 24 stands for the manufacturer, and the last 24 represents the NIC number

2. Describe the main operating principle of the switch?

The switch receives the data frame, first checks whether the source MAC address of the data frame exists in the MAC address table, does not add;

The destination MAC address of the data frame is present in the Mac surface, and if there is one, it is forwarded directly, not in addition to the source port. Its

After the secondary switch learns the host MAC address corresponding to the port, if the host for this MAC does not participate in communicating this entry for 300 seconds

will be removed and the host MAC address corresponding to the port will be re-learned if a change occurs.

3. What are the types of Cisco and H3C switches that are commonly used today? What is the price?

Product System Unit Price

cisco2960 Series Switches About 5k

CISCO3560 Series switches about 2w

CISCO4500 Series switches about 5w

CISCO6500 Series switches around 20w

(H3C) smb-s1248 48-Port full Gigabit Two-layer non-managed enterprise class

Rack-mounted switch around 1.8k

(H3C) SMB-S1848G-CN 48 Port full Gigabit two Layer network management core 2.3K or so

Switch

4. Can the switch set the gateway? How do I configure the gateway for the switch?

The switch can set the gateway

In global configuration mode: IP default-gateway gateway IP address

The purpose of the switch configuration gateway is to enable computers of different network segments to manage the switch remotely.

Day 05

1. What is the function of the subnet mask, the default subnet mask, the default network ID, the broadcast address, and the number of available IPs?

1) Subnet mask

Function: The network bit and the host bit used to differentiate the IP address

Calculation: The network bit with a continuous 1, the host bit with a continuous 0 representation

2) Network ID

The IP address of the network bit is unchanged, and the host bit is represented by a continuous 0

3) Broadcast Address

The broadcast address of the IP address is calculated: The IP of the network bit is unchanged, and the host bit is represented by a continuous 1.

Broadcast address for IP address: The last address of the IP address network segment (that is, the maximum value of the segment)

4) Calculation of the number of available host IPs

2 host Party Precedence-2

2. What is routing? How does the router work?

Routing: The process of forwarding packets across an internetwork from a source host to a target host.

How routers work: Select the best path based on the routing table, and each router maintains a routing table, which is the router forwarding

The key to the packet, each routing table record indicates which physical port the router should be sent to, by

This port can reach the address of the next router on that path.

3. How is the routing table formed?

Getting the routing table

1), Direct Connect route: Configure IP Address, port up status, form Direct connect route.

2), non-directly connected network segment: requires static or dynamic routing to add a network segment to the routing table

4. What are the characteristics of static routing and dynamic routing? List several common dynamic routing protocols?

Static routing Features: Manually configured by the administrator, is one-way, so need to be on the edge router between the two networks

Side to the point, otherwise it will cause the flow to go without back, lack of flexibility, suitable for small networks.

Dynamic routing is characterized by dynamic routing, which communicates with each other in the network, transmits routing information, and uses the received routing information to

The process of a new routing table is implemented based on a routing protocol. The common routing protocol types are: Distance vector routing protocol (e.g.

RIP) and link-state routing protocols (such as OSPF). Routing protocols define some of the rules that routers communicate with other routers.

5. What is a floating route? What is the default route?

Floating Routing: Configure a static route that manages a greater distance, as a backup path for an emergency trigger, in the case where the primary route is valid,

Floating routes do not appear in the routing table.

Default route: The default route is a special static route, which is also referred to as the "default gateway" Duyu the host of the peripheral network.

The destination network for the default route is 0.0.0.0/0.0.0.0, which matches any destination address, only if no

The default route is used when the routing entry is not correct.

Day 06

1. What are the characteristics of the Transport layer protocol?

Some necessary problems of computer network in Linux system