What Is DNS?
DNS (Domain Name System) is the internet's directory of websites. It matches the words we type like "google.com" with the numbers computers need to find sites.
Websites all have an IP address, which is a set of digits that acts like a location code. Humans prefer using names, but computers need numbers to connect. DNS bridges this gap by translating between the two.
When you type a website address into your browser, DNS looks up the IP address for that site and returns the number sequence. This allows your computer to locate and display the right webpage.
So while we see brand names like Facebook, behind the scenes DNS has associated those with numeric IPs. This system is essential for surfing the web seamlessly. It lets us use easy-to-remember labels for sites while computers route traffic using coded sequences.
How does DNS work?
DNS works by querying different servers to uncover the IP address hidden behind a domain name. It's a step-by-step investigation.
When you type a site name into your browser, your computer asks your internet service provider's (ISP) DNS resolver to find the dots-and-numbers address. The resolver first checks its own short-term memory to see if it already knows.
If not, it contacts the root servers at the top of the DNS hierarchy. The root provides the address of the next server down, which handles the ".com" or ".org" part of the website name.
The resolver then jumps to that TLD server to get passed along again, getting closer to the name server in charge of the full website address.
This chain of referrals continues, with each server pointing to the next one down, until the IP address is finally retrieved.
So DNS lookups work like a treasure hunt, with intermediate servers providing maps to the next clue until the resolver can piece together the exact location. The IP is then sent back through the chain to your computer.
A Brief History of DNS
Before DNS existed, connecting online required manually tracking internet addresses on each computer. This hosts file linked network names to complex number sequences. Updating it to add a new device or site meant editing every single machine.
In the early 1980s, technologists conceived an automated telephone book to coordinate addresses across systems. Published documentation by Mockapetris and Postel (1983) outlined the Domain Name System to replace static host files.
The first DNS software was launched in 1984. Originally, its role focused on converting website names into IP numbers for easy connection. Instead of memorizing number strings, users could type a name like Wikipedia.org.
Over time, DNS grew more versatile and secure. It enabled finding servers via text records, email routing, and risk-reduction layers like DNSSEC encryption. The 1983 vision simplified networking by centrally organizing name-to-address mappings that were once manual and local.
Now DNS had dynamic global directories that expanded from resolving IPs to wider connectivity and safety issues. The hierarchical system could assign details without touching each host file everywhere.
DNS servers involved in a webpage loading
When you load a webpage, multiple DNS servers are involved in resolving the domain name to an IP address. Here are four examples of DNS servers that may be involved:
Recursive DNS server
This is the first DNS server that your device contacts when you request a domain name. It checks its cache to see if it already has the IP address for the domain name.
If it doesn't, it queries other DNS servers in the hierarchy to obtain the IP address.
Root name server
If the recursive DNS server doesn't have the IP address for the domain name, it will query one of the root name servers.
These servers are responsible for directing queries to the appropriate top-level domain (TLD) name servers.
TLD name server
The root name server responds to the recursive DNS server with the IP address of the TLD name server for the requested domain name.
The TLD name server is responsible for directing queries to the authoritative name server for the domain.
Authoritative name server
The authoritative name server is the final DNS server in the hierarchy that contains information about the IP address associated with the requested domain name.
It responds to the recursive DNS server with the IP address, which is then provided to your device to connect to the website.
These four DNS servers work together to quickly and efficiently resolve domain names to IP addresses, enabling you to access websites and other online resources.
Difference between an authoritative DNS server and a recursive DNS resolver
An authoritative DNS server and a recursive DNS resolver are two different types of DNS servers that play different roles in the DNS resolution process.
An authoritative DNS server is responsible for providing answers to DNS queries about a particular domain name.
It contains information about the IP addresses associated with the domain name and is considered the "source of truth" for that domain.
When a DNS resolver receives a query for a particular domain name, it will eventually contact the authoritative DNS server for that domain name to obtain the IP address.
On the other hand, a recursive DNS resolver is responsible for querying DNS servers on behalf of a client device to resolve a domain name to an IP address.
It receives a DNS query from a client device and then recursively queries other DNS servers to obtain the IP address for the domain name.
The resolver caches the results of its queries to speed up future DNS resolutions for the same domain name.
The main difference between an authoritative DNS server and a recursive DNS resolver is that an authoritative DNS server provides answers to DNS queries about a specific domain name, while a recursive DNS resolver queries other DNS servers on behalf of a client device to resolve a domain name to an IP address.
Difference between DNS resolver, DNS server, and DNS lookup
DNS resolver, DNS server, and DNS lookup are all related to the Domain Name System (DNS), which is responsible for translating domain names into IP addresses.
However, they refer to different components and functions within the DNS system.
A DNS resolver is a software component or service that resides on a client device, such as a computer or smartphone and is responsible for sending DNS queries to a DNS server.
A DNS server, on the other hand, is a computer or network device that stores DNS records and responds to queries from DNS resolvers.
When a DNS resolver sends a query to a DNS server, the server looks up the requested domain name in its database and returns the corresponding IP address to the resolver.
DNS lookup, also known as a DNS query, is the process of requesting information from a DNS server about a specific domain name.
This process involves sending a DNS query to a DNS resolver, which then sends the query to a DNS server. The DNS server searches its database for the requested domain name and returns the associated IP address to the resolver.
What are the steps in a DNS lookup?
Here are the steps involved in a DNS lookup:
The user enters a domain name into their web browser.
The computer sends a DNS query to a DNS resolver, which is typically provided by the user's internet service provider (ISP).
The DNS resolver checks its cache to see if it already has the IP address for the domain name. If it does, it returns the IP address to the computer.
If the DNS resolver doesn't have the IP address in its cache, it sends a DNS query to a root name server.
The root name server responds to the DNS resolver with the IP address of a top-level domain (TLD) name server.
The DNS resolver sends a query to the TLD name server for the IP address of the next name server in the hierarchy.
This process continues recursively until the DNS resolver reaches the authoritative name server for the domain name.
The authoritative name server responds to the DNS resolver with the IP address for the domain name.
The DNS resolver caches the IP address and returns it to the computer.
The computer uses the IP address to connect to the server hosting the website associated with the domain name.
These steps ensure that the computer can locate the correct IP address associated with a domain name, allowing it to connect to the website.
DNS lookups happen quickly and efficiently, enabling users to access websites and other online resources.
What are the types of DNS queries?
There are several types of DNS queries that can be made by a client device to obtain information about a domain name. Here are some of the most common types:
A records query - This type of query is used to obtain the IP address associated with a domain name.
MX records query - It is used to obtain information about the mail server associated with a domain name.
CNAME records query - This type of query is used to obtain information about the canonical name associated with a domain name.
NS records query - It is used to obtain information about the authoritative name servers for a domain.
SOA records query - This type of query is used to obtain information about the start of authority (SOA) record for a domain.
PTR records query - This query is used to obtain the domain name associated with a particular IP address.
What is DNS caching?
DNS caching stores website addresses in a temporary memory bank. When your computer needs to find a website's location, it first checks this bank.
If the address is there, your computer doesn't need to ask other servers. It just pulls the address from storage and loads the site faster.
The goal is quicker access by eliminating extra steps. Instead of always asking around, your computer relies on recent history.
As long as the details remain in temporary holding, you skip the usual back-and-forth queries. This makes multiple visits to the same sites quicker.
DNS caching works by storing the results of previous DNS queries in memory for a specified period of time, known as the time-to-live (TTL).
The TTL is set by the authoritative name server for the domain name and specifies how long the DNS resolver should cache the query result before it expires.
Caching is essential for DNS performance, as it reduces the time it takes to resolve DNS queries and minimizes the load on DNS servers in the hierarchy.
It also helps to ensure the availability of DNS information even if some of the DNS servers in the hierarchy are temporarily unavailable.
However, DNS caching can also cause problems if the cached information is out of date or incorrect.
In some cases, changes to DNS records can take time to propagate through the DNS system, and cached information can continue to be used even after it has become stale.
This can result in users being directed to the wrong IP address or experiencing other DNS-related issues.
Where does DNS caching occur?
DNS caching can occur at several different levels in the DNS resolution process:
Local device cache
Client devices such as computers and smartphones often have their own DNS cache, which stores the results of recent DNS queries.
This allows the device to quickly retrieve the IP address associated with a domain name without having to send a new query to a DNS resolver.
Recursive DNS resolver cache
DNS resolvers provided by ISPs or other organizations typically have their own cache to store the results of recent DNS queries.
This allows the resolver to quickly retrieve the IP address associated with a domain name without having to query other DNS servers in the hierarchy.
Authoritative name server cache
Authoritative name servers for a domain may also cache DNS query results to improve performance and reduce the load on their servers.
When an authoritative name server receives a DNS query, it checks its cache to see if it already has the IP address for the domain name.
Intermediate DNS caches
In addition to the above, intermediate DNS caches may also exist between the recursive DNS resolver and the authoritative name server.
These caches may be operated by ISPs or other organizations and are used to improve DNS performance by reducing the number of DNS queries that need to be sent to authoritative name servers.
DNS caching at each of these levels can help to improve DNS performance and reduce the load on DNS servers.
However, it is important to ensure that cached information is accurate and up-to-date, as outdated or incorrect information can lead to DNS-related issues.
Is DNS secure?
The DNS is generally considered to be secure, but it is also vulnerable to various types of attacks that can compromise the security and integrity of the system.
One of the main security issues with DNS is DNS spoofing or cache poisoning, which involves an attacker sending false DNS information to a DNS resolver, causing it to return incorrect information to clients.
This can lead to users being directed to fake websites or other malicious resources.
Another security issue with DNS is DNS hijacking, which involves an attacker taking control of a domain name by modifying the DNS records associated with it.
This can allow the attacker to redirect traffic intended for the legitimate domain to their own malicious servers.
To mitigate these and other security threats, various security mechanisms have been developed for DNS, including DNSSEC (DNS Security Extensions), which provides cryptographic validation of DNS responses to prevent spoofing and other attacks.
In addition to DNSSEC, other security measures for DNS include the use of firewalls, intrusion detection and prevention systems, and secure protocols such as DNS over HTTPS (DoH) and DNS over TLS (DoT) to encrypt DNS queries and responses and protect them from interception and manipulation.
Overall, while DNS is not immune to security threats, there are many tools and techniques available to help ensure the security and integrity of the system, and ongoing efforts are being made to improve DNS security and resilience in the face of evolving threats.
How to find my DNS server?
There are several ways to find out which DNS server your device is currently using:
Check your network settings: On a Windows computer, you can check your DNS server settings by going to Control Panel > Network and Sharing Center > Change adapter settings > Properties > Internet Protocol Version 4 (TCP/IPv4) > Properties.
On a Mac, go to System Preferences > Network > Advanced > DNS. Your DNS server address should be listed in these settings.
Use command prompt or terminal: On a Windows computer, you can use the command prompt to view your DNS server address by running the command "ipconfig /all". On a Mac, you can use the terminal and type the command "scutil --dns". This will display the DNS server address currently being used.
Use online tools: There are several websites that can help you determine your DNS server, such as DNS Checker and What's My DNS Server.
It's important to note that your DNS server may be automatically assigned by your internet service provider (ISP), or you may have manually configured it to use a specific DNS server.
If you're experiencing issues with your current DNS server, you may want to consider changing it to a different server that may provide better performance or security.
Does DNS service affect SEO and how?
DNS itself does not directly affect SEO, but issues with DNS can indirectly impact SEO by affecting website accessibility and performance.
DNS itself does not directly impact SEO rankings. However, DNS issues can create problems that hurt optimization indirectly.
If DNS is misconfigured, websites might load slowly or go down. These lags frustrate visitors, making them leave quickly. Bad user experience signals search engines that a site lacks quality.
DNS weaknesses like hijacking can also falsely flag sites as unsafe. Even temporary security issues spook search crawlers, suggesting technical problems.
While not an SEO factor on its own, good DNS means solid site infrastructure and trustworthiness. By enabling smooth, uninterrupted website connections, webmasters remove barriers to good rankings. Smooth DNS keeps websites running reliably to showcase their full optimization potential.