Full form of DNS: – The DNS is a central part of the Internet that provides a way of matching names (a website that searches for) with numbers (the website address).
Everything related to the Internet (laptops, tablet PCs, cell phones, websites) is an internet protocol address (IP) that is made up of numbers. Your favorite website may have an IP address of 64,202,189,170, but obviously not easy to remember. However, a domain name like bestdomainnameever.com is something that people can recognize and remember.
Full Form of DNS
The full form of DNS is Domain Name System.
What Does DNS Stands For?
DNS stands for Domain Name System.
Abbreviation for Domain Name System
Abbreviation for Domain Name System is DNS.
Acronym for Domain Name System
Acronym for Domain Name System is DNS.
Synchronize DNS domain names with IP addresses that allow people to use memorable domain names while computers on the Internet can use IP addresses. The Domain Name System (DNS) is the Internet phone directory.
People access information online through domain names such as nytimes.com or espn.com. Web browsers interact via Internet Protocol (IP) addresses. DN S translates domain names into IP addresses so that browsers can load Internet resources.
Each device connected to the Internet has a unique IP address that other computers use to locate the device. DNS server eliminates the need for people to memorize IP addresses such as 192.168.1.1 (IPv4) or more complex and new IP addresses Alphanumeric 2400: CB00: 2048: 1:: C629: d7a2 (IPv6). Let’s examine what makes thousands of millions of Internet users and 351.8 million domain names * connect, and how Verisign helps to make this happen.
In loading a webpage, there are 4 DNS servers involved;
The Recursor can be considered a librarian who is asked to search for a particular book somewhere in the library. The DNS Recorder is a server designed to receive queries from client computers through applications such as web browsers. Normally, the precursor is responsible for making additional requests to comply with the client’s DNS query.
Root name server:
The root server is the first step to convert (resolve) readable hostnames into IP addresses. You can consider it as an index in a library that refers to different shelves of books, usually as a reference to other more specific places.
TLD name server:
The top level domain server (TLD) can be considered as a particular set of books in a library. This name server is the next step to find a specific IP address and it hosts the last part of a hostname (on example.com, the TLD server is “com”).
Authorized name server:
This definitive name server can be considered as a dictionary on a shelf where you can translate a name given to its definition. The authorized name server is the last stop in the name server query. If the authorized name server has access to the requested record, it returns the IP address of the requested hostname to the DNS registrar (librarian) who made the original request.
What is the difference between an authorized DNS server and a recursive DNS resolution system?
Both concepts are related to the servers (server groups) that are integrated into the DNS infrastructure, but each one performs a different function and they are stored in different places in the pipeline of a DNS query. One way to notice the difference is to have the recursive resolver at the top of the DNS query and the authorized name server at the end.
Resolve recursive DNS
The recursive resolver is the computer that responds to a recursive request from a client and takes the time to locate the DNS record. This involves a series of requests until the authorized DNS name server for the requested record is reached (or a timeout occurs or an error is returned if no record is found).
Fortunately, recursive DNS resolvers do not always require multiple requests to find the records needed to respond to a client. Caching is a data persistence process that short-circuits the required requirements by providing the resource record previously requested in the DNS lookup.
Authorized DNS server
In simple terms, an authorized DNS server is a server that actually contains and is responsible for DNS resource records. This is the server at the end of the DNS search string that responds to the record of resources queried and, ultimately, allows the web browser to reach the IP address required to access a website or other web resources.
An authorized name server can respond to requests from its own data without having to consult another source since this is the ultimate source of truth for specific DNS records.
What are the steps in a DNS search?
In most cases, DNS is a domain name that is translated to the appropriate IP address. To see how this process works, you can follow the path of a DNS lookup when you go from a web browser through the DNS lookup process and vice versa. Let’s look at the steps.
Note: Often, DNS lookup information is cached locally on the polling computer or remotely in the DNS infrastructure. A DNS search usually consists of 8 steps. By caching DNS information, the steps in the DNS lookup process are skipped, which speeds up the search. The following example shows the 8 steps if there is nothing in the cache.
The 8 steps in a DNS lookup:
- A user types “example.com” into a web browser and the query goes to the Internet and is received by a recursive DNS resolution system.
- The resolver then queries a DNS root name server (.).
- The root server responds to the resolution server with the address of a Top Level Domain (TLD) DNS server (for example, .com or .net) that stores the information of its domains. When looking for example.com, our request is directed to the .com TLD.
- The resolver requests the .com TLD.
- The TLD server then responds with the IP address of the domain name server, example.com.
- Finally, the recursive resolver sends a request to the domain name server.
- The name server returns the example.com IP address to the resolution server.
- The DNS resolution system responds to the web browser with the IP address of the originally requested domain.
Once the 8 steps of the DNS search return the IP address for example.com, the browser can execute the request of the web page: The browser sends an HTTP request to the IP address.
The server with this IP address returns the web page that will be played in the browser.
What is a DNS resolution?
DNS resolution is the first step in the DNS search and is responsible for dealing with the client who made the first request. The resolver initiates the poll order, which finally translates a URL to the required IP address.
Note: A typical DNS search without a cache includes recursive and iterative queries.
It is important to distinguish between a recursive DNS query and a recursive DNS resolution system. The query refers to the request to a DNS resolution system that requires the resolution of the query. A recursive DNS resolution system is the computer that accepts a recursive query and processes the response when making the necessary requests.
What types of DNS queries are there?
A typical DNS search finds three types of queries. By using a combination of these queries, an optimized process for DNS resolution can reduce the distance traveled. In an ideal situation, the cached record data is available so that a DNS name server can return a non-recursive query.
3 types of DNS queries:
Recursive query: a recursive query requires a DNS client to respond to a DNS server (usually a recursive DNS resolution) with the requested resource record or an error message if the resolution can not find the entry.
Iterative query: in this situation, the DNS client allows a DNS server to return the best possible response. If the DNS server queried does not match the name of the query, it returns a reference to a DNS server that governs a lower level of the domain name space. The DNS client then searches for the reference address. This process continues with other DNS servers in the query chain until an error or timeout occurs.
Non-recursive query: this usually occurs when a DNS resolver queries a DNS server for a record that it has access to because it is authorized for registration or the record exists in the cache. Typically, a DNS server caches DNS records to avoid additional bandwidth consumption and uploading of the upstream server.
What is DNS caching? Where does DNS caching take place?
The purpose of caching is to temporarily store the data in a location that improves the performance and reliability of data requests. DNS caching keeps the data closer to the client that requests it, allowing the DNS query to be resolved earlier and avoiding additional queries in the DNS search chain, improving loading times and reducing the use of DNS. bandwidth / CPU. DNS data can be cached in several locations, each of which stores DNS records for a certain period of time determined by a TTL (Time-to-Live).
Browser DNS caching
Modern web browsers are designed by default to cache DNS records for a specific period of time. The purpose here is obvious; The closer the web browser’s DNS caching is, the less processing steps must be performed to validate the cache and make the correct requests for an IP address. When a DNS record is requested, the browser cache is the first place to search for the requested record.
If you are the user of Chrome Browser on your pc, then you can see the status of your DNS cache in chrome: // net-internals / # DNS.
DNS caching at the operating system level
- The operating system’s DNS resolution system is the second and last local stop before a DNS query leaves your computer. The process in your operating system developed for this query is commonly referred to as an “auxiliary code resolver” or DNS client. When a stub resolver receives a request for an application, it first checks its own cache to see if the registry exists. Otherwise, a DNS query (with the recursive flag set) is sent out of the local area network to a recursive DNS resolution system within the Internet service provider (ISP).
- If the recursive resolver within the ISP receives a DNS query as in all previous steps, it also checks if the translation from host to requested IP address is already stored in its local persistence layer.
- The recursive resolver also has additional capabilities, depending on the types of records in its cache:
- If the resolver does not have the A records, but the NS records for the authorized nameservers, these nameservers are consulted directly, without going through several steps in the DNS query. This link prevents the search of root and .com nameservers (in our example.com search) and helps resolve the DNS query more quickly.
- If the resolver does not have NS records, it sends a query to the TLD servers (in our case .com) and omits the root server.
- In the unlikely event that the resolution does not contain any records that refer to the TLD servers, the root servers are consulted. This event usually occurs after a DNS cache has been removed.
- If the Internet was very, very small, it was easier for people to assign specific IP addresses to certain computers, but that did not last long as more devices and people joined the growing network. In addition to creating a directory for all of these devices, words were used to connect to different sites. For most people, remembering words is easier than remembering a set of numbers. It is also possible to enter a specific IP address in a browser to access a website.
How DNS servers work
- The DNS directory that compares the name with the numbers is not in a place in a dark corner of the Internet. Like the Internet, the directory is distributed throughout the world and stored on domain name servers, all of which communicate regularly to provide updates and redundancies. With more than 332 million domain names listed by the end of 2017, a single directory would be very large.
- DNS resolution converts a hostname (for example, www.example.com) to an easy-to-use IP address (for example, 192.168.1.1). Each device on the Internet is assigned an IP address. This address is necessary to find the right Internet device. For example, a street address is used to find a specific house. When a user wants to load a web page, a translation must be made between what a user enters in their web browser (example.com) and the easy-to-use address required to locate the example.com website.
- To understand the process behind DNS resolution, you must know the various hardware components that must pass a DNS query. For the web browser, DNS searches are performed “behind the scenes” and do not require interaction with the user’s computer, except for the first request.
· To more than one IP address, each named site can correspond. In fact, some sites have hundreds or more IP addresses that correspond to a single domain name. For example, it is likely that the server your computer reaches for www.google.com is completely different from the server that another user from another country would reach if you entered the same site name in your browser.
· Another reason to distribute the directory is the time it would take to get an answer if you were looking for a site if there was only one location for the directory, shared by millions, probably billions, people. We will also be looking for information at the same time. That’s a long line to use the phone book.
· In contrast, DNS information is shared among many servers, but it is also cached locally on client computers. You can be using google.com several times a day. Instead of having your computer ask the DNS name server for the IP address of google.com each time, this information is stored on your computer, so you do not need to access a DNS server to resolve the name with your IP address. Additional caching can be produced on the routers used to connect clients to the Internet, as well as on the user’s Internet Service Provider (ISP) servers. With so many caching operations, the number of requests that are actually sent to DNS name servers is much smaller than it seems.
How DNS increases efficiency.
· DNS is organized in a hierarchy that guarantees a fast and smooth flow. As an illustration, let’s say you want to visit networkworld.com. The initial request for the IP address is to a recursive resolver, a server normally operated by an ISP or another third party. The recursive resolver knows what other DNS servers it needs to resolve the name of a site (networkworld.com) with its IP address. This search leads to a root server, which knows all the information about top-level domains such as .com, .net, .org and all the domains of countries such as .cn (China) and .uk (United Kingdom). Root servers are located all over the world, so you will usually be directed geographically to the nearest one.
· Once the request reaches the correct root server, it is forwarded to a top-level domain name server (TLD), where second-level domain information is stored. These words are used before accessing .com, .org, .net (for example, this information for networkworld.com is “network world”). The request is forwarded to the domain name server, which contains the information about the site and its IP address. Once the IP address is discovered, it is sent back to the client, who can now use it to visit the site. All this takes only milliseconds.
· Since the DNS has been working for more than 30 years, most people take it for granted. Security was also not taken into account when configuring the system. The hackers have taken advantage of all this and unleashed a variety of attacks.
DNS reflection attacks
DNS reflection attacks can flood victims with high-volume messages from DNS resolution servers. Attackers request large DNS files from any open DNS resolver that they can find using the victim’s fake IP address. When the resolvers respond, the victim receives an avalanche of unsolicited DNS data that overwhelms their computers.
DNS cache poisoning
Poisoning the DNS cache can redirect users to malicious websites. Attackers can insert incorrect address records in the DNS. When a potential victim requests an address resolution for one of the poisoned sites, the DNS responds with the IP address of another site controlled by the attacker. These fake websites can lead victims to reveal passwords or malware downloads.
DNS resource exhaustion
Overloaded DNS resources can clog the DNS infrastructure of ISPs and prevent Internet service provider customers from reaching the websites. This can be done if the attackers register a domain name and use the victim’s name server as the dominant domain server.
If a recursive resolver cannot provide the IP address associated with the site name, the victim’s name server is consulted. Attackers generate a large number of requests for their domain and discard nonexistent subdomains for boot, which causes a large number of resolution requests to be activated on the victim’s name server and overwhelm them.
What is DNSSec?
- The DNS Security Extensions try to make the communication between the different server levels involved in DNS lookups safer. It was developed by the Internet Corporation for Assigned Names and Numbers (ICANN), the organization responsible for the DNS system.
- ICANN became aware of vulnerabilities in communication between top-level, second- and third-level DNS directory servers that could allow attackers to misuse searches. In this way, attackers could respond to queries from legitimate sites with the IP address of malicious sites. These websites can upload malware to users or perform phishing and pharming attacks.
- DNSSEC would solve this by digitally signing your requests at each DNS server level. This ensures that the requests sent by the end users are not ordered by the attackers. This creates a chain of trust so that each step of the search verifies the integrity of the request.
- In addition, if domain names exist then DNS sec can determine. If this is not the case, this fraudulent domain cannot be forwarded to innocent applicants seeking to resolve the domain name.
- As more domain names are created, as more devices join the network through the Internet of Things and other “smart” systems, and as more sites migrate to IPv6, more important is maintaining a DNS ecosystem healthy. With the growth of Big Data and Analytics, the need for DNS management is also increasing.