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Networking Basic Part 3- DNS Server

Updated: Oct 10





This basic knowledge series is in progress for those who start up about computer networking and learners. After two articles presenting the hub and switch router, the content of this article discusses the functioning of DNS servers (domain name systems).

This is also the final part of how computers share the normal IP address range in the network segment. Invite you to follow.


Fundamental DNS server knowledge


What is a DNS server?

Why do I need a DNS server?

DNS server and malware

More information about DNS servers

DNS Root Server


What is a DNS server?


As we all know, when a computer needs to get information on a computer on a different network or network segment, it needs the help of the router. The router transfers the required data packet from one network to another (such as the Internet). If you have read the second part, we have given an example that refers to the IP address associated with the website.


To access this website, your web browser must know the IP address of the website. The browser then provides the router address, the router will determine the route of another network and the appropriate target will request the data packet to the host. Each website has an IP address, but you can visit these websites every day regardless of its number. In this article, we will show you why this is possible.





Ip address is like a home address. This includes network location (which is enabled in the network segment); and device location (identifying a particular computer in a network), which is like a house number. For TCP/ IP default communication between two computers, it is necessary to know the IP address.


When you open the web browser and enter the name of the website (known as a domain name or URL (Universal Resource Locator), the browser will go directly to the website without passing through the website. By entering the IP address. You can imagine that opening a website is like a process of mailing to the address shown on the cover of the post office.


The IP address in network communication acts as an address on the cover. If you just type the recipient's name and "forget" their address, the mail cannot reach the right location. The same is the case with the website coming and opening. Your computer cannot contact the website unless it knows the IP address of the website.


But you do not need to type in an IP address and you can open the correct website you want when entering the browser domain name. So where is the IP address? The process of "translating" the domain name into the IP address is the function of the DNS server (domain name system server).


DNS server is a server that has a database of public IP addresses and hostnames associated with them. In most cases, the DNS server converts or converts domain names to IP addresses as required. DNS servers run special software and communicate with each other using special protocols. To put it simply: The DNS server on the Internet is a device that converts the Quantum.com URL you entered into the browser's address bar to IP address 123.30.180.60.





Note: Other names for DNS servers include name server/ name server and domain name system server (domain name system server).

In the previous two articles, we have covered some concepts of the Computer's TCP/ IP configuration, such as IP addresses, subnet masks and default gateways. View Figure A


Below for another configuration option called "Preferred DNS Server".(Reference domain name system server).


Figure A: The DNS server option of the selection is defined as part of the TCP/ IP configuration on the computer.

As you can see in the diagram, the option "Preferred DNS Server" is defined as part of the TCP/ IP configuration. This means that the computer will always know the IP address of the DNS server. This is very important because the computer is not in the TCP/TCP. Cannot interact with another computer using IP protocols.



Why do I need a DNS server?

The question can be answered with another question: Do you find it easy to remember 123.30.180.60 or quantriamng.com? Most people will answer that remembering phrases like series is much easier than a series of numbers.



When you enter tridevcomputer.com in your web browser - you just need to remember https://tridevcomputer.com/ URL. The same is true for any other website like Google.com, Amazon.com, etc. We are human, so we can easily remember the words in the URL more easily than the IP address numbers.


Other computers and network devices will be responsible for understanding the IP address. Therefore, the DNS server plays a role in helping users use a memorable name to access the website, and also helps the computer use an IP address to access the website. The DNS server is an "interpreter" between the hostname and IP address.


Now we will see what happens when you visit a website. The process begins by opening the web browser and entering a URL. Then, the browser knows that it cannot only find a website based on the URL. Thus, it asks for the IP address information of the DNS server from the Computer's TCP/ IP configuration and submits the URL path to the DNS server. DNS server will view URL path on a table with the IP address list of website. It then returns the IP address for the web browser and the browser can contact the requested website.





This explanation may be a little simpler. Domain name resolution in DNS can only work if the DNS server has a record that is compatible with the requested website. If you visit random websites, the DNS server will not have any records of this website. This is because the Internet is very large. Millions of new websites and websites are created every day. A single DNS server can maintain with each website and respond to all requests from anyone with an Internet connection.


Now suppose that a single DNS server can store records for each website that exists. If the server's capability is not problematic, the server will overflow everywhere through name resolution requests received from Internet users. Centralized DNS servers are often highly popular targets for attacks.


As a result, DNS servers are often shared across multiple sites, avoiding the same DNS server to provide a name resolution for the entire Internet. Today, the Internet Corporation for Associated Name and Number (or ICANN) is the organization responsible for the allocation and registration of Internet domain names in the world. Managing domain names for the entire network is such a big enterprise, so ICN responds to domain names to different companies. For example, the Network Solutions domain handles ".com". But that does not mean that network solutions maintain a list of IP addresses associated with all.com domains. In most cases, the network contains the DNS server records of the solution that indicates DNS servers that are considered official for each domain.


THE IP ADDRESS OF THE DNS SERVER THAT IS RESPONSIBLE FOR THE DOMAIN NAME WITH THE.COM EXTENSION. It will return this address to the browser and will send a request to a specific DNS server in the process of returning.


The highest DNS server level. COM-end domain names may not know which IP address of the website is being requested, but it knows the IP address of the official DNS server for domain brienposey.com. Returns the address to the machine that requested. The web browser then sends a DNS query to the DNS server that has the power to the requested domain. and this DNS server will return the IP address of the website, which will allow the machine to communicate with the requesting website.


As you can see, many steps are required for the computer to find the IP address of the website. To reduce the number of DNS queries, the results of these questions are usually stored for several hours or days, depending on how the machine is configured. Caching IP addresses increase the function and reduce the total amount of bandwidth used by DNS queries. You can imagine how bad web browsing would be if your computer had to complete a full set of DNS queries when looking at a new web page.


DNS server and malware


It is very important to run the antivirus program. One reason is that malware can change DNS server settings to attack your computer. And this is something you don't want to be.

For example, your computer is Google's DNS server 8.8.8.8 and 8.8.4.4. Visiting your bank's website (with bank URL) in these DNS servers will allow you to log in to your account properly.


However, if the malware changes your DNS server settings (which can happen without your knowledge) by entering a single URL can take you to a completely different website or a similar website. The website you need to visit is not. This fake banking website may sound like real, but instead of letting you log in to your account, it records your username and password, which gives it all to the attacker. Information about your bank account.

However, malware that enters your DNS server usually redirects popular websites to websites filled with ads or fake virus sites, which makes you think you have to buy a program to do so. Clear infected computer.





You should do two things to prevent the prey from becoming prey. First, install anti-virus programs so that the malicious programs are removed, and they can do any harm. Secondly, pay attention to what the website looks like. If it is slightly different from normal or you get an "invalid certificate" message in your browser, it may be a sign that you are on a fake website.



More information about DNS servers


In most cases, two DNS servers, primary servers and secondary servers are automatically configured on your router and/or computer when connecting to ISP via DHCP. If one of these fails, you can configure two DNS servers, the device will use the secondary server.

While many DNS servers are managed by ISPs and are only used by customers, some public servers are also available. See the DNS server list for details and how to change DNS servers - if you need help making changes.


Some DNS servers can provide faster usage time than others, but your device depends on how far your device reaches the DNS server. For example, if THE ISP's DNS servers are close to Google's DNS servers, you can find that addresses are quickly resolved using the default servers from your ISP, using the default servers from your ISP, using third-party servers.





If you have a network problem that cannot load a web page, there is a problem in the DNS server. If the DNS server cannot find the appropriate IP address associated with the hostname you entered, the web page will not load. Also, this is because the computer communicates through one


The IP address is not a hostname, so the computer does not know what you are trying to reach until it can use the IP address.


DNS server settings are "closest" to the device that applies. For example, when your ISP can use a set of DNS servers that apply to all the routers associated with it, your router can use a separate set of DNS server settings for all of them. The device is connected to that router. However, the computer connected to the router can use its DNS server settings to override the settings of both the router and THE ISP. Tablets, phones, etc. are the same.


The article above describes how malicious applications can control your DNS server settings and that servers redirect your website requests elsewhere. Sure, scammers can do something, but they are also found in some DNS services like OpenDNS - of course, with good intentions. For example, OpenDNS can redirect adult websites, gambling sites, social networking sites, etc. to "blocked" pages, but you have full control over redirects.

the nslookup command used to ask your DNS server.


Let's open the command prompt tool and then write down:

nslookup tridevcomputer.com

And the result will be the same:



In the example above, the nslookup command tells you the IP address (or an IP address in this case), which you can translate the address you entered into your browser's search bar.


DNS Root Server


Several DNS servers are part of the connection of the computer, which we call the Internet. Most importantly, 13 DNS root servers store a complete database of domain names and their associated public IP addresses.

These high-level DNS servers are named with the first 13 characters (A through M) of the alphabet. Ten of these servers are in the United States, one in London, one in Stockholm and one in Japan.



Finish

In this article, we explain how DNS servers are used to resolve domain names for IP addresses. Although the described process seems quite simple, you should note that the ICN and high-level DNS registrars use load balancing technology to distribute requests to multiple DNS servers. Second. This prevents servers from overflowing and removes the possibility of a point of failure.





Related : Networking Basics: Part 4 - Workstation and Server
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