Routery
Viznachennya DNS (Domain Name System, “domain name system”) is a computer distributed system for collecting domain information. The main area of operation of this system is the conversion of the host name into the IP address and the provision of data about mail routing.
Host - be it any computer or server, connections up to
local measures
to the Internet.
Robot principle
- A schematic representation of the process of assigning an IP address by domain name to be entered
- The operation of DNS is simple, but it is through ignorance of its basics that most of the problems arise when transferring an existing domain name and registering a new one.
- We'll spend a little time describing the circuit itself.
- When a user launches a web browser and enters the name of a website’s domain, his PC is forced to contact the Internet provider’s DNS server to retrieve the IP address on which the domain is located (1).
- If the provider's DNS servers do not detect in their cache information about the site that is being queried, then the query is forced on the root DNS servers (2).
- The root DNS server searches its database for information about the name servers of the hosting provider on which site is present.
Next, it reports their cached DNS server of the provider (3).
Also, if someone from your Internet provider accesses the site and then changes the IP address or name server, then in the provider’s database, which caches the DNS server, the old information will be lost, the documents will not be cached update.
Until now, when you access the site, you will receive outdated information about your location (IP addresses).
However, users from other providers can access the site using a new IP address.
Basically, if you have a good description of the situation in your video, then it’s not good to show off.
The trace must be logged for an hour to update the information on the root DNS servers and the provider’s DNS servers.
In the meantime, you can independently determine the correctness of setting up your domain about any problem, or get technical support. Diagnosis and detection of problems Diagnosis of problems and their severity are reviewed in the statistics DNS is a service that ensures communication between
in different segments
boundaries.
This station allows you to significantly reduce your work hours while searching for information.
In this article you will learn about the basic principles of the operation of the service, as well as the methods and forms of data transmission on the Internet.
- Yak pratsyuє
- At the dawn of the development of the Internet, there was a “flat” hiring system: the skin doctor had a large file, which contained lists of necessary contacts.
- If you connect to the World Wide Web, your data is sent to other devices.
- However, due to the rapid development of the Internet, it was necessary to simplify the exchange of data as much as possible.
- Therefore, it was divided into smaller segments-domains.
- In my opinion, the stench spreads to the subdomain.
- At the top of the address, submitted in a named form, there is a root - the main domain.
- The fragments of the Internet are an American development, there are two types of primary domains:
illegal domains that comply with US regulations:
com - business organizations;
This dovzhina does not have to exceed 63 characters, and the last dovzhina of the address is 255 characters.
Basically, the Latin alphabet, numbers and hyphens are used, and as a result, prefixes based on other writing systems began to be used.
The case of letters does not matter. Servers are computers that host the transfer of other objects in the middle of one level of communication, which allows you to speed up the exchange between clients. The stench became the basis of the new system.
Skin rhubarb limits may be
Vlasny server
to place information about the addresses of the clients in your segment. Searching for the required data is done like this:
DNS Basics
- A vuzol that consists of many domains is called a zone.
- This file contains the main parameters of your segment. This also includes information about the FQDN or the assigned domain name.
- If the entry ends with a dot, this means that the object name is set correctly. There are several types of computers that can serve DNS:
- master- Leading agent of the border.
You can change its configuration;
slave
- - Vlashtuvannya is of a different order. They serve clients equally with the master and can replace him in case of malfunctions. This allows the boundary to be developed; cashewy.
- Post information about domains of third-party zones; invisible.
Not included in the zone description.
- Most often, this status is given to players with master status in order to protect them from attack. The customer can send one of two types of requests to them.
- The browser forces it through the resolver program: recursive.
If the server does not contain the necessary information, then the necessary data is retrieved from the computers
of all things
and forces the client to confirm. This allows you to change the number of requests and will save time on your traffic; iterative.
Prote this very cleverly, from the computer you can change the domain name, or change the address.
In addition, the same IP address can be shared with all domain names.
However, a domain can contain information about more than one IP address.
- Robot mode Servers can run in the following modes:
- maintenance of the damp zone.
- Data exchange takes place between the head and side computers. In this case, non-authoritarian koristuvachs are not accepted;
recursive nutrition viconanny;
forwarding – the server tries to write to another zone. Changing DNS settings
Define the parameters and set them according to the framework
automatic mode
.
To send your data, you need to go to the “Meter connections” section.
After this, you need to go into the protocol that is used to maintain the measure.
- In the “Power” section you can specify the necessary parameters.
- Please specify the main IP address of the server and the alternative one.
- Notification format
- Messages that are used to exchange information with the service begin with a 12-byte header.
- Then follows the identification field, which allows you to determine which query the match was found for.
- The flags field (currently 16 bits) includes the information:
- type of notification;
transaction code;
Identification of authoritativeness (this shows that the service computer is due to the limit);
TS-ensign.
It appears that we have received information about circumcision or otherwise. ensign of recursion, then. You can send messages to computers in good order to the server;
ensign of the possibility of recursion.
- Shows whether the server is running or notified by redirection;
- turning code.
- It appears that a confirmation was sent with no pardons.
- The remaining 16-bit field shows the number of parameters to be covered.
Request in DNS requests
Partially, I’ll sign up for the resource at Vdguku
There is no way to convey information about the party that sent the notification.
You have the following data: confirmation, server importance and
additional information
This is a list of the main programs that the vikory service uses.
Within the same domain, these records are unique.
- At different levels, there may be duplicates of these records. This data includes the following types of records:
- SOA
- - Let's start with renewed importance. It allows you to set up a domain and computer to serve you.
- They also contain information about the relevance of the cached version and the contact person who maintains the singing level server; And change the IP address and the type of hosts.
- They allow you to identify the resource address in the domain; NS (Name Server)
- enable the transfer of computers that serve the domain; SRV (Service)
- display all resources that represent the most important functions of the service; MX (Mail Exchanger)
Allows you to automatically configure the data feeder for computers that serve you within the same domain;
PTR (Pointer)
search for the name of the resource, since the user knows its IP address; CNAME (Canonical Name)
Allow the server to identify itself under a number of service aliases.
Keshuvannya
To search for necessary information, the browser can search for information in three segments.
Right now, the necessary data can be found using an additional DNS service. on the local level. You can find out if the computer contains the Hosts file.
However, if the operation is not successful, the client submits a request.
To quickly retrieve information, cached servers are used.
This protocol is also used by secondary servers if they collect data from the main computers for three years in order to learn about the update of the configuration file.
The DNS service has a complex hierarchical structure.
However, the server system will ensure communication between all the computers and devices of Merezh.
To find out the necessary information, the client forces the request. Please enter basic information about the object you are clicking on and the computer that serves the service area.
For this exchange, the UDP and TCP protocols are used.
Domain names
consists of at least two parts (marks), separated by points. The numbering of marks is carried out from right to left.. All the next marks are subdomains, then. hosting is a subdomain of the web-3 domain, and web-3 is a subdomain of the ru domain. The numbering of marks is carried out from right to left.. All the next marks are subdomains, then. Mentally, such a floor can stretch for 127 levels. Any tag can consist of (maximum) 63 characters, but the domain name cannot exceed 254 characters, including periods. However, action and theory, apparently, are different, and domain registrars often set authority limits.
To respond to the requested information, the DNS protocol stops UDP or TCP port 53. When the information is requested and ready, the form is filled with UDP data. The numbering of marks is carried out from right to left.. All the next marks are subdomains, then. And TCP is disabled for AXFR requests and responses over 512 bytes. In order to find out the IP address of the site you want to contact, you need to quickly use the ping command. If you are using the Windows XP operating system, click "Start" - "Viscont" ( Use the keys win+r) and type the command in the row cmd . Show up at the end
command line
.
Dial a command from her ping and the site, for example, ping the site.
In the rows that appear after pressing Enter, enter the group of numbers 87.242.76.. It is important to remember that IP addresses are not the same as hostnames. One computer can host a large number of websites, but this is not to say that a host with a single IP address can host a whole list of names.
Similarly, up to one name can be associated with different hosts.
- This is how the regulation of vantagement is achieved.
- In order to increase the stability of the system, a large number of servers must be introduced into the robot to accommodate the new data.
- So, the world has 13 such servers.
- The skin is related to any territory.
- Data about them is available on any operating system, as long as such servers do not change the original address.
- SOA (start of authority record) is a record that is sent to the server, which is consistent with standard information about the presentation domain.
It is necessary to say about reserved domains(Reserved Top Level DNS Names).
RFC 2606 specifies that domain names need to be specified as a model (which is especially important in documentation) and during testing.
For example, you can search for test.com, test.org, test.net, as well as invalid, example, etc. When thinking about domain names, you can guess that they can be formed from a small set of ASCII characters. It is possible to dial a domain address independently from the language, as the correspondent says.
That’s why such names are international. ICANN has ratified the IDNA system, which is based on Punycode. You can convert any phrase into Unicode using a character set that is possible for correct DNS work. Here are some ways to set up DNS programs in BIND (Berkeley Internet Name Domain), MaraDNS NSD (Name Server Daemon), DJBDNS (Daniel J. Bernstein's DNS), PowerDNS Microsoft DNS Server (for server versions) operating systems Windows NT).
- To find out who the person is, whether by domain or IP address, it is enough to be victorious.
edge protocol
whois (from English who is – “who?”). The seed of the idea that the creation of this system had germinated was not allowed to be destroyed system administrators Find the data of other administrators, IP addresses and domains.
None of the domain names are recognized as unregistered on the domain name, so it is not possible to find any secretly available information about them on this service.
Viznachennya Translation Dear reader, see this picture IPv6 People are often obsessed with domains.
Why is my site not working?
Why is this crap broken, nothing helps, I just want it to work!
The great advantage of DNS is that it is a public service and you can go to the server if you want to connect. Let's try it.).
I have a domain petekeen.net, which is hosted on the machine web01.bugsplat.info.
Commands that are listed below can be run from the OS X command line (
oh, that’s macOS, - approx. Prov. Let's take a look at the mapping between names and addresses:
; <<>$dig web01.bugsplat.info<<>The dig command is the Swiss Army Nizh for DNS queries.<<- opcode: QUERY, status: NOERROR, id: 51539 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
Cool,
richly functional tool
. Axle of the first part of the line:> DiG 9.7.6-P1
> web01.bugsplat.info;;
Global options: +cmd;;
Got answer: ;;
->>HEADER
There is only one important detail here: information about the request.
It is said that we requested the recording and received one answer.
Axis:<<>$dig web01.bugsplat.info<<>> +trace web01.bugsplat.info;;
Global options: +cmd .
137375 IN NS l.root-servers.net.
.
The next block shows how to dig by selecting the default root server and requesting an A-record for web01.bugsplat.info.
It is visible only to the IP address of the root server (192.5.5.241).<<>So what is the root server?<<>Let's find out!<<- opcode: QUERY, status: NOERROR, id: 2862 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;241.5.5.192.in-addr.arpa. IN PTR ;; ANSWER SECTION: 241.5.5.192.in-addr.arpa. 3261 IN PTR f.root-servers.net.
$dig-x 192.5.5.241;
> DiG 9.8.3-P1 > -x 192.5.5.241;; Global options: +cmd;;
Got answer: ;; ->>HEADER Prapor -x zmushuє dig to perform a gate search for the IP address.
DNS identifies the PTR record that connects the IP and host, in this case f.root-servers.net.
Turning to our front line, the root server F turns to another set of NS servers.
Vіn represents the top-level domain info.<<>$dig web01.bugsplat.info<<>dig requests the A record for web01.bugsplat.info from one of these servers, and retrieves another set of NS servers from the output, and then requests from<<- opcode: QUERY, status: NOERROR, id: 18765 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;petekeen.net. IN MX ;; ANSWER SECTION: petekeen.net. 86400 IN MX 60 web01.bugsplat.info. ;; Query time: 272 msec ;; SERVER: 192.168.1.1#53(192.168.1.1) ;; WHEN: Fri Jul 19 20:33:43 2013 ;; MSG SIZE rcvd: 93
one z cich
server record A for web01.bugsplat.info. . And, if you decide, I will remove the evidence!
Ugh!<<>$dig web01.bugsplat.info<<>A lot of traffic would have been generated, otherwise all the records would have been permanently cached by the skin server at Lanciuzhku.<<- opcode: QUERY, status: NOERROR, id: 16785 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;www.petekeen.net. IN A ;; ANSWER SECTION: www.petekeen.net. 86400 IN CNAME web01.bugsplat.info. web01.bugsplat.info. 300 IN A 192.241.250.244 ;; Query time: 63 msec ;; SERVER: 192.168.1.1#53(192.168.1.1) ;; WHEN: Fri Jul 19 20:36:58 2013 ;; MSG SIZE rcvd: 86
Your computer also caches this data, just like your browser.
Most often, DNS queries never reach the root servers, so their IP addresses may never change (
“It’s funny, there’s still talk about the great TTL for recordings from their database.
The reason is that DNS performs replacement in such a way that all records in the location where the CNAME indicates are also valid for the CNAME.
In our case, records from www.petekeen.net and web01.bugsplat.info will be saved.
Therefore, it is not possible to work with a CNAME on the root domain on the petekeen.net platform, because you need other records there, for example, MX.
Ask for other servers
It is clear that the DNS configuration is zipped.
You think you have fixed the problem, but you don’t want to check when the cache is updated to reconfigure.
Using dig, you can set up a public DNS server instead of your default one, like this:
$dig www.petekeen.net @8.8.8.8
The @ symbol with the IP address or the host will be written to the specified server through the port behind the connection.
You can use Google's public DNS server or the Level 3 public server at address 4.2.2.2. Typical situations Let's take a look at typical situations that are well known to web developers.
Redirect domain to www
It is often necessary to redirect the iskettlemanstillopen.com domain to www.iskettlemanstillopen.com.
A registrar like Namecheap or DNSimple is called this
URL Redirect
.
Axis butt for Namecheap admin:
The @ symbol means the root domain iskettlemanstillopen.com.
Let's marvel at the A record for this domain:
The Internet is a process in which each personal computer is assigned a personal number, which is called an IP address.
Digital addressing turned out to be not the most convenient at the dawn of the development and formation of the Internet, so it was decided to use letters for writing addresses.
Also, if a person wants to go to any site, they should enter letters, not numbers. 
The problem is that the computer can only accept information from a digital view - the sequence of zeros and ones.
It is a priori impossible to comprehend the information in the appearance of letters. 
Therefore, a service was created, the main task of which was to translate the lettering of the address into the form of numbers.
Unfortunately, domain name systems began to develop tools to verify the integrity of the data being transmitted. 
These funds began to be called Security Extensions.
The information that is transmitted is not encrypted, but the reliability of the data is verified using cryptography methods.
The new standard, called DANE, conveys reliable cryptographic data.
Then they are used to install secure and theft connections of transport and application levels.
Domain and server owners are responsible for periodically updating DNS firmware to ensure reliable verification and adequate protection of the information being transmitted.
Otherwise, the safety and reliability of the data may not be guaranteed.
What functions does the DNS provide? 
What is DNS and what are the functions of its protocol?
What does DNS do?