Why would I care about DNS?
Often overlooked, the term 'DNS' stands for 'Domain Name System'. This is the global hardware and software worldwide decentralized infrastructure that stores crucial pieces of information for each domain on Internet.
This is how, since its creation in 1983 by Paul Mockapetris, we can access a website by remembering its domain name and humain-redeable URLs instead of its IP addresses. This is also thanks to this system that we can create and use email addresses.
The data that a domain manager publishes in the DNS system is stored in form of DNS records.
We made it pretty straightforward. Enter the complete domain or sub-domain (e.g. 'developers.google.com') you want to lookup and optionally focus on a specific record type with the drop-down list.Just press 'DIG' and launch the query!
Who stores my DNS records?
When you buy a domain name, you should first verify the NS (Name Servers) records that typically defines the different servers that are storing a copy of your active DNS zone. In many cases, if you didn't modify the default NS records linked to your domain, the values are already pointing to your registrar's DNS servers managing your active DNS zone. If you have special needs, and, for example, want to make CloudFlare manage your DNS zone, you'll need to update your NS records with the ones provided by CloudFlare in order your visitors can connect to the valid zone.
But who's then storing your NS records? The TLD Root Servers are a network of computers dedicated to manage the NS records of all domain names based on the TLD extension (e.g. .com, .net, .org, .tools, .de, etc.) they're representing. Also depending on the specific TLD, they are the entities defining the TTL (Time-To-Live) of the NS records values. From the moment the cached values expire in the TLD Root Server, it'll need to query your domain's registrar for the fresh SN records values.
All the other records of your DNS zone also have a specific TTL. Those TTL values definitely matter as they are defining, usually in seconds, the amount of time during which the corresponding record values can get cached in several layers of the DNS system, such as the ISP, custom DNS server, local proxy or even the browser of your visitors. Resolving DNS can be time consuming, which makes many ISPs and DNS Service Providers to create local caches that contain domain's already resolved records. These are primarily the addresses they already fetched from Root Servers and other Name Servers at some point of time. Thanks to that technology, when you send a request for a URL, instead of repeating the initial complete chain of DNS ping pong, your browser will obtain this domain information much closer and faster.
Make it the best compromise between performance and reliability, specially when planning any future DNS updates.
What are DNS records?
Your domain's DNS zone is simply a table of public values and a DNS record is one of its lines. This is no more than pure text stored on many servers. It is lightweight and powers the Internet.
DNS record types
When it comes to resolving DNS records, G Suite.Tools' DNS Lookup can display information about wide record types as explained in the sections below.
Name Server records indicate which servers store your active DNS zone. They are your authoritative name servers.
A records return a 32-bit IPv4 address. Those are most commonly used to map domains to the IP address(es) of their respective website. But it is also used for DNSBLs and storing subnet masks. Generally, A records map a FQDN - Fully Qualified Domain Name - to an IPv4 address.
AAAA records return a 128-bit IPv6 address. This is the IPv6 analogy of A records.
CNAME, which stands for Canonical NAME, serves as the alias of one name to another. Thus, G Suite.Tools' DNS Lookup will continue by retrying the lookup with the new name. The name server basically handles these queries differently from a direct A record.
Mail Exchanger records map a domain name to a list of MTAs (Message Transfer Agents). Those MX records are needed for any email reception. For example, if you have an email address like 'firstname.lastname@example.org', you'll need at least one MX record defined on the host 'my.domain.com' to start receiving emails.
Text records are meant for arbitrary human-readable text in a DNS record. However, this record-type more often carries machine-readable piece of information, such as specified by RFC 1464, opportunistic encryption, Sender Policy Framework, or any other standards and techology.
Start Of Authority records basically specify authoritative information about a DNS zone, including the primary name server, the email of the domain administrator, the domain serial number, and several timers relating to refreshing the DNS zone.
Pointer records serve as a pointer to a Canonical NAME. Unlike a CNAME, DNS processing stops and only the name is returned. Its most common use is for implementing reverse DNS lookups, but it can also help for DNS-SD.
HINFO records specify the host's type of CPU and Operating System. This information can be used by application protocols such as FTP, which use special procedures when communicating with computers of a known CPU and OS type.
Service records are used for newer protocols instead of creating protocol-specific records such as MX or SPF.
Naming Authority PoinTeR records basically allow RegExp-based rewriting of domain names which can then be used as URIs, further domain names to lookups, etc.
- Use WHOIS to discover the owner of any domain or IP.
- Use the Location Explorer to find in which city a website is actually hosted.