Shulou(Shulou.com)06/03 Report--

> 1. The two standard wire sequences for making twisted pair are:

T568A: green white, green, orange white, blue, blue white, orange, brown white, brown

T568B: orange white, orange white, green white, blue, blue white, green, brown white, brown.

3. If a company applies for a Class C IP address, but needs to connect 6 subsidiaries, the largest subsidiary has 26 computers, and each subsidiary is placed in a network segment, then the subnet mask should be set to 255.255.255.224.

4. If it is known that the IP address of a host is 201.103.136.184 and the mask of its subnet is 255.255.255.192, the host is in a _ c _ class network, and a maximum of _ 63 hosts are allowed in the subnet.

5. What's the difference between PAT and NAT?

Answer: all are network address translation, but the difference is that one is one-to-one and the other is one-to-many reusable address translation. PAT is a kind of nat. The Chinese full name of NAT is address translation, which generally refers to the one-to-one correspondence between internal IP and internal global IP; the Chinese full name of PAT is port translation, which generally refers to the one-to-many correspondence between internal IP and internal global IP.

9. A computer in the local area network cannot access the file server through UNC, prompting that the path cannot be found, but other clients can access it normally. How to solve this problem?

A: you have to see if that machine and the others are in the same network segment, and you can PING the other party's IP**** first.

twelve。 What is FTP and port number SSH,TELNET,SMTP,POP3,DNS windows server what is the default port for remote desktops

21 22 23 25 110 53 3389

03. What is the structure and function of MAC addresses?

The structure is the custom number of the first half, which is divided into the manufacturer code and the second part, and the length is 48bit

The function is: on a global scale, the only one that represents a network hardware device

04. What is the purpose of ARP?

Based on the IP address, the corresponding MAC address is obtained in order to realize the fast encapsulation of the data frame.

Communication within the same network segment is called "switching"

08. How does the switch work?

1) form the MAC address table

When the switch receives a data frame on a port, it associates the source MAC address in the data frame with the incoming port to form an MAC address table entry

2) find the MAC address table

The switch compares the destination MAC address in the data frame with the MAC address table entry. If the corresponding entry can be found, it is forwarded out based on the port; if no corresponding entry is found, it is broadcast (that is, sent from a port other than the incoming port)

09. What is routing?

Communication between different network segments is called "routing"

10. What is the difference between TCP and UDP?

TCP links are stable, but link establishment is time-consuming and delayed.

UDP transmits data quickly, but it is easy to lose data and is unstable.

8. The common ideas of network troubleshooting and the function or purpose of each step.

First ping the loopback address to check whether the TCP/IP driver is working.

Then ping other hosts in this network segment to check whether the private network communication is normal.

Then ping the default gateway to check whether the egress route is normal.

Then ping other hosts in other network segments to check remote connectivity.

9. Please list the types of commonly used dynamic disks and the corresponding number of disks required, disk utilization, performance characteristics, and redundancy.

Simple volume, 1 disk, 100% utilization, no change in performance, no redundancy

Spanned volumes, 2-32 disks, 100% utilization, no change in performance, no redundancy

Striped volumes, 2-32 disks, 100% utilization, improved read and write performance, no redundancy

Mirrored volumes, 2 disks, 50% utilization, reduced read and write performance, redundancy

RAID5, 3-32 disks, utilization = number of disks-1, reduced read and write ability, redundancy.

10. What do the following domain names represent in the top-level domain?

Gov: government departments

Com: business sector

Edu: education Department

Net: network service structure

Mil: military department

Org: civil society organization.

10. Combined with the DNS query method, please explain the complete DNS parsing process.

Enter the domain name you want to access in the browser. The browser first accesses its own hosts file to see if there is a mapping relationship. If it exists, it calls directly to complete the resolution. If it does not exist, it sends the access request to the local domain name server. After receiving the request, the local domain name server queries its own cache record. If there is a record, it returns the result directly. If there is no record, the local domain name server will send the request to the root domain name server. after receiving the request, the root domain name server will return the IP address of the corresponding top-level domain name server according to the top-level domain. After receiving the returned top-level domain name server IP address, the local domain name server will send the request to the top-level domain name server. After receiving the request, the top-level domain name server queries its own cache record, if it cannot be resolved. The address of the subordinate domain name server is returned to the local domain name server again. After receiving the address, the local domain name server repeats the above action until the domain name server address in the request is queried. After receiving the resolution record, the local domain name server will first cache a copy, and then send the resolution result to the client. After receiving the result, the client can directly access the web page under the domain name.

1. Why can't the switch isolate the broadcast domain

Because the switch is a layer 2 device, it can only view the MAC address in the data frame, but each network segment is a broadcast domain, and the network segment belongs to layer 3, so it cannot be isolated.

2. Types of vlan

Port-based static VLAN dynamic VLAN based on mac address.

3. Why are there 4096 vlan?

Because vid occupies 2 bytes, consider 2 to the power of 12 equals 4096.

4. Hosts with the same vlan can belong to different physical locations or on different switching devices.

01. What is VLAN?

VLAN, which refers to virtual local area network, is a two-layer technology. Broadcast domain isolation can be achieved on the switch. Thus, the impact of data broadcast storm on the switching network can be reduced, the difficulty of network management can be reduced, and the flexible expansion of network scale can be realized.

02. What is the difference between a Trunk link and an Access link?

Trunk links can support data forwarding of multiple VLAN at the same time.

Data carries VLAN tags (except native vlan)

Access links can only transmit data of one VLAN at a time.

The data sent and received have no tags.

03. What is the hybrid port in a Huawei switch?

Hybrid port, called hybrid / promiscuous port. Is the default mode for Huawei switch ports. It can realize not only the function of access link, but also the function of trunk link. The label carried by the data forwarded on the port can be flexibly controlled.

04. What STP protocol?

STP, which refers to spanning Tree Protocol. When there are redundant links in layer 2 network, it is used to prevent the occurrence of layer 2 data forwarding loop.

05. Describe how STP works

By default, the switch turns on the STP function. After power on, the BPDU is sent and compared with each other with the connected switch to ensure that there is only one shortest, loop-free, layer 2 data forwarding path to any device in the network.

The specific process is as follows:

# first determine the role of the switch: root switch and non-root switch

# secondly, determine the role of the port: root port, designated port and non-designated port

# finally determine the status of the port: down, listening, learning, forwarding, blocking

07. What are the encapsulation protocols for Trunk links?

802.1Q and ISL.

The former is a public standard, which adds 4 bytes to the original data.

The latter is a Cisco proprietary protocol that adds 30 bytes to the original data.

1. What is the default route:

Is a special route, which is divided into two types, one is dynamically formed, and the other is manually configured by the administrator.

2. When will the default route be used

Default routes are used only if no explicit matching entries can be found in the routing table.

3. What is the longest route matching principle.

When there are multiple routes to the same network segment, choose the most detailed route to match.

4. What is floating route and its function.

Is a special static route that can change the priority. Redundant backup and load balancing of links can be realized.

08. How does a router work?

After receiving the packet, match the "routing table" entry based on the destination IP address in the IP header. If the match is successful, it will be forwarded on the corresponding interface. If the match fails, the packet will be discarded.

09. What is a gateway?

That is, the exit when one network segment goes to another.

10. What is SVI?

SVI, which refers to the switched virtual port, represents the layer 3 IP interface corresponding to a VLAN, which is generally used as the gateway IP for all member hosts in the VLAN.

13. What are the roles and status of switch ports in RSTP?

-Port role: root port, designated port, alternate port (instead of root port),

Backup port (the specified port is backed up)-Port statu

Learning: learning status; forwarding: forwarding status; discarding: discarding status

14. What is the purpose of GVRP?

GVRP, the generic VLAN registration protocol, is a public protocol.

It is mainly used to automatically synchronize VLAN information between switches to ensure the consistency of the VLAN information database on the switch.

15. What is the purpose of DHCP?

By setting up a DHCP server, it automatically assigns IP addresses and other related parameters to the terminal host, so as to realize the batch allocation and management of IP addresses and improve the management efficiency.

16. There are several versions of RIP. How does it work?

RIP is divided into RIPv1 and RIPv2

Principle:

After the router runs the RIP protocol, it periodically sends RIP update messages on the port on which the process is started, ensuring that the RIP databases saved between the routers are fully synchronized.

After receiving the RIP message, the router puts it into the RIP database and selects the best route entry to put into the routing table. When the network changes, RIP will quickly send update messages to notify other RIP routers. Used to ensure the stability and connectivity of the entire network.

01. What is the purpose of VRRP?

VRRP, which refers to the virtual gateway redundancy protocol. The function is to form virtual gateway IP addresses between different gateway devices, so as to achieve backup redundancy between gateway devices and enhance the stability of the gateway.

02. What is the purpose of NAT?

NAT, which refers to network address translation

The function is to realize the translation between the private IP address of the internal network and the public IP address of the external network, so as to realize the interworking between the internal network and the external network. at the same time, it can hide the structure of the internal network and enhance the security of the network.

03. What are the types of NAT?

Static NAT,

Dynamic NAT, in which the package also contains the commonly used PNAT (port NAT)

04. What are the roles and types of ACL and the differences?

ACL, which refers to access control lists

The function is to match the interested traffic and filter the traffic with tools.

Basic ACL and extended ACL.

Difference:

The basic ACL can only match the source IP address in the IP header; the extended ACL can match both the source IP address and the destination IP address in the IP header, as well as the content of the transport layer protocol, and control the traffic more accurately.

05. What is the purpose of OSPF?

OSPF, which refers to the open shortest path first protocol.

The function is to quickly form a shortest, loop-free, three-layer forwarding path within the corporate network.

06. What is the working process of OSPF?

# first build the OSPF adjacency table

# second, synchronize OSPF database

# finally calculate the OSPF routing table

07. What is the status of OSPF establishing neighbors?

# down, port does not have OSPF protocol enabled

# init, initialization status

# two-way, two-way communication status

# exstart, exchange initialization status

# exchange, exchange status

# loading, loading status

# full, full adjacency status

08. Which layer of OSI does OSPF belong to? How do you express it? What are the message types?

OSPF belongs to layer 3 of OSI, and the protocol number is 89

The message types are:

 Hello: hello package for neighbor establishment, maintenance, and demolition

 DBD: database description message for reliable database synchronization

 LSR: link-state request message, which is used to implement the request for database entries

 LSAck: link-state acknowledgement message, which is used to acknowledge LSU and LSR messages and to achieve reliable transmission of messages.

10. What is the purpose of OSPF virtual links?

The purpose of OSPF virtual links is to connect non-backbone areas to area 0.

11. What are the special areas of OSPF?

Stub region

Totally stub region

NSSA region

Totally NSSA region

01. Which layer of the OSI model does BGP belong to?

BGP is located at layer 7 of OSI and the socket is TCP 179.

02. What is the purpose of BGP?

It is mainly used between different networks to realize the flexible control of routing.

03. What is the internal anti-ring mechanism of BGP?

IBGP split horizontally. **

It means that routes received from an internal BGP neighbor will not be sent to another IBGP neighbor again.

04. What are the solutions for split horizon for IBGP neighbors?

# the first solution: full interconnection of IBGP neighbors

# the second solution: IBGP Alliance

# the third solution: IBGP routing reflector

05. Which tables are included in BGP?

# BGP neighbor Table

# BGP database

# BGP routing Table

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.