After working for three years, I discovered that these online terms that are constantly being used every day are always being misunderstood.
Hey! Brothers! I recently found out while talking to a few veteran internet workers who worked longer than my router.
Good guy! Someone took it.WLANandWANConfusion. someone's connected.pingThe underlying principles of the commands are stuck, and some even think thatCDNyes“Tracking number”The abbreviation（not a joke, really）
Let me be honest, although web workers depend on real work to eat, if the basic concepts are cooked into a pot of porridge, they are beaten in the face when checking for faults in a minute. For example, a customer asks you“Why does the local area network transfer files faster than the external network?”You can't stop talking.“because……Is the wire thick?”Oh, right?
We're going to start basic literacy today,15A knowledge point can be interpreted in a spoken language to help you digest vague concepts.
Find out what's wrong, and we'll fix what you don't understand!
For more information, please scan the WhatsApp QR code below to contact customer service.
01 LAN
Local Area Network
Scope :company , home , classroom and other small circles , up to a few kilometers .
Features :Play with your own people , data is transmitted within a small range , fast(For example, you use your company intranet to communicate10GBDocuments can be sent to customers faster than WeChat.100Double)
Analogy :It 's like you and your co-worker are in the same office , and the network cable/A wireless network can transmit files to each other without being connected to the Internet and without interfering with each other.
02 WAN
Wide Area Network
Scope :cross-city , cross-country , such as Beijing and Shanghai servers , rely on it .
Features :It is a long-distance line , the speed is faster thanLANSlow（after all , it has to cross mountains and seas ）, but it can scatterLANGet connected.
Analogy :it 's like taking a bus from your hometown to the provincial capital ,LANIt's your neighborhood,WANIt is a long-distance road connecting various communities. Without it, you can't connect to the far places.“The Internet World”.
03 VLSM
Variable Length Subnet Mask
Function :Take a bigIPSegments of the network, cut into subnetworks of different sizes(For example, put a sentence like this192.168.1.0/24to cut up3A small network segment for different departments)
Why it matters :Don 't wasteIPThe address! For example, you have100One device, traditional subnet division may give you a division254individualIP(Waste)154One)，VLSM It can be precisely distributed and cut on demand.
Analogy :it 's like having a job in a company ,VLSMyesHR, can be based on the number of departments（set ofequipment ）allocate different sizes of the area , small departments to10A job position, given by a large department.50No, don't waste an inch of space.
04 VLAN
Virtual Local Area Network
Function:on a switch, virtual group of equipment, such as sales and technical department of the computer can not communicate（anti-fish？No）, mainly to isolate broadcast domains and improve security.
How to play :Set up different computers for different departmentsVLAN ID(The sales are, for example,VLAN 10The technology is.VLAN 20）Without permission, don't try to cross districts.
Analogy :it 's like having a big office with a glass wall in it“Sales Department”and“Department of Technology”, although we are physically on the same floor（ the same switch ）, but the data can only be in their own department , can not casually cross-functional chat .
05 WLAN
Wireless Local Area Network
The essence:LANThe wireless version, use.WiFiSignals instead of network wires. For example, your router isWLANThe core is there.
Disadvantages :The signal is like a girlfriend 's patience . It weakens through walls and can 't go very far(To wear it)3Internet speed plummeted after a wall. I know everything.
ComparisonWIFI：WLANIt's a technical standard（IEEE 802.11），WIFIIt is a certified trademark.(Like the one you connected to.)“ChinaNet”yesWIFIWhat's being used behind that?WLANTechnology)
06 WIFI
Wireless Fidelity
In layman 's terms :what you search on your phone“CMCC”“TP-LINK_XXX”It's all okay.WIFIOh, yeah.WLANThe landing form is what it takes.
Cold knowledge:WIFIAn alliance-certified device can be calledWIFIOtherwise, I'll just call you.WLAN（ But we use them interchangeably every day and no one really cares , like Coke and carbonated drinks ）.
Analogy:WLANIt's the recipe for hot pot,WIFIIt's Haidilao hot pot.——The former is a technology, the latter is a specific application for which a trademark has been applied.
07 SMTP
Simple Mail Transfer Protocol
Role :It is responsible for sending emails , such as when you click Send , the email is sent from your mail server to the other party 's mail server , relying onSMTP。Disadvantages:Only responsible for delivery, not responsible for confirmation of receipt（the other party's email is full and can't be received？It will only report an error, not like a courier to call you）.
Analogy :it is equivalent to the transport link when you send express ,SMTPBe responsible for sending mail packages from.AThe post office arrived.BA post office, but no matter.BIs there a vacancy at the post office for delivery?
08 VPN
Virtual Private Network
Role :Public network(Airport, for example)WiFi）Tunnel on to your data encryption, pretend you're on the company intranet, secure access to internal systems.
Scene :Working from home , connecting to the company 's serverVPNOr else you can't get in.(Just like a corporate building needs a work license,VPNThat's your virtual work license.
Warning :Don 't use freeVPN! Worse than a roadside ad, stealing your data in minutes(Serious companies use paid versions, such as Convincing,Cisco）
09 ICMP
Internet Control Message Protocol (ICMP)
Function :Transmits network control messages , such as“Goals can be reached”“to exceed the time limit”“The Internet is not accessible.”Oh, yeah.IPThe little assistant to the protocol.
Classic applications:pingThe command depends on.ICMPhair“echorequest”Wait for the other person to come back.“echoReply”Measure the delay and lose the bag.
Analogy:ICMPIt's the traffic police in the cyber world that's responsible for telling the data packet.“There 's a traffic jam ahead（overtime ）”“This road is closed（ impassable ）”，pingIt's just a handy traffic cop.
10 PING
Packet Internet Groper
Role :Send a small package to ask the other side“Are you there?”Yes, we can measure latency.（such aspingBaidu shows“40ms”That's the round-trip time.40In milliseconds)And the rate of bag loss（such as“Losing the bag.0%”I just didn't lose my bag.
Newbie Mistake:Don't“ping”We played it like this.“Spell”Once a new person asked.“Why can't I spell it?”Input method - Bring a large pot（buildA direct account of the negotiations“pingIt's a web version.‘Hello?’”）
Analogy:Just like when you call your colleague's name in the hallway and he answers, it means he's in the office。No response for half a day, may have slipped to the toilet（high network delay）or quit（device offline）.
11 TRACERT
Trace Route
Function :Check data fromAreachBWhat are the transit stations（ routers ）, such as you visit the TikTok card , usetracertYou can see where a jump（ which router ）stuck .
Comparisonping：pingJust to tell you.“Can I get there?”，tracertLet me tell you.“How to go, where the traffic jam”Barrier removal must be provided!
Analogy :it is equivalent to using Gaode Map to check“What intersections are used from the company to the airport?”，pingyes“Can I get to the airport?”，tracertyes“Specific route and waiting time for each traffic light”
12 CDN
Content Delivery Network
Function :It stores copies of video , pictures and other resources in many places in the country . When you visit , it makes the nearest spare tire server send resources to you , and the speed is very fast .
Scene :you seeBstation1080PThe video was fast, all thanks to.CDNIf a video site suddenly gets stuckPPT, may be the spare tire is not enough（sectionpoint broke ）.
Analogy :it 's like ordering takeout ,CDNIt is a national chain warehouse , close to you to ship , than from the headquarters（ source server ）shipping fast10A thousand times.
13 DNS
Domain Name System
Function :put to“www.baidu.com”This memorable domain name translates to“14.215.177.38”thisIPAddress（ computers only know numbers , people can 't remember ）.
Importance :NoDNSYou have to memorize websites all over the world.IPAddresses are more painful than memorizing English words(such as BaiduIPYes.110.242.68.4Can you remember that?）
Analogy:DNSIt's the online version.114Check the station. you check it.“McDonald's”Well, it tells you the McDonald's phone number.（IPAddress), and then you can call（ visit the website ）.
14 ACL
Access Control List
Function :Filter data packets according to rules , such as“prohibitIPfor192.168.1.100My computer accesses the Internet”“Only allowed.80Port（ web ）traffic through”。
Scenario :The company wants to ban employees from using TikTok at work , so itACLShut down Douyin's port orIPIt's more efficient than administrative follow-up.100A thousand times.
Analogy :equivalent to the security guard in front of the company , see your work card（ data packet information ）: no work card（does not conform to the rules ）？Don't let in! Looking for a sale?Use the right channel（allow specific ports）
15 NAT
Network Address Translation
Function :Allow multiple devices to share a public networkIPto go online(Because of the public network)IPIt's too expensive, like the company has.100Just buy a computer.1A public networkIPOh, come on.NAT “translation”Divided by different port numbers)
Scene :your home3A mobile phone+ 2One computer is connected at the same time.WiFiTo get online, a router is a router.NATTranslation officer, keep all your devices private.IP（192.168.1.x）Public networks translated into routersIPAdd different port numbers(For example, cell phones)AUse port1000The computer.BUse port2000）
Analogy :it 's like having multiple employees in a company share a door number(Public Internet)IP）When the courier arrived,NATshout“Zhang 3, your delivery is at.101Room! Li 4, you're here.102Room!”Oh, come on.“Room Number”（end ofmouth ）distinguish between different devices .
Today's interactions:Which term have you been stuck with? Let's say, for example, take this“VLAN”Listen to me.“WAN”When configuring, turn the car over? Talk in the comments section and make the brothers happy ~
