How the domain name system works: the big domain glossary part 2
Why does a website appear after entering the domain? Where are domain and website information saved and how are they connected? In this article, our big domain glossary tells you everything you need to know about the domain name system (DNS), root server and IP address.
Domain name system (DNS): The DNS is a an internet registry that works similarly to the Yellow Pages. For one name, there may be one or more telephone numbers (IP addresses) on file. This is necessary to access services in the internet. The DNS enables calls to a website by following an internet address (URL) or sending an e-mail to a certain receiver. For example, if you send a request to the internet via the domain www.1and1.com, the URL is converted into the respective IP address (e.g.: 192.0.2.42) via the DNS and and is lead to the corresponding computer.
Furthermore, the DNS is a register for additional information about services connected to a domain. With this, it can be determined if a computer works as an e-mail server for the domain or if the domain’s respective name servers should be called.
Root server: The root name server (root server) is like the brain of the domain name system. Every device that is connected to the internet receives a specific server name which is translated to a domain names such as “blog.1and1.de” into an IP address. If a name server has no information about the queried TLD, it forwards the request to a superordinate root server. Here, the name server responsible for the TLD is determined. This root zone, a kind of global domain registry, includes domain names and IP addresses of all TLD name servers and is the centerpiece of the net communication infrastructure. In total, there are 13 root servers with different operators centrally coordinated by ICANN.
Root zone: This zone defines the address of the domain tree in the domain name system for which a name server (NS) is responsible. The root zone contains more than 1500 gTLDs, ccTLDs and IDNs, which are transmitted to the root server database.
URL: The “uniform resource locator” is the standard for calling content. URLs are mainly used to access websites. By typing in a URL, the browser knows what site to open or search for. In addition to websites (http), a URL can also call a data server (ftp), an e-mail address (mailto) or a file (file).
IP address: When accessing the internet, every computer receives a unique, global IP address. This 32-bit number is built in a certain pattern and has a value between 0 and 255. An IP address that is fixed to a domain is called a static IP address. When a computer receives a new IP address each time it accesses the internet, it is called a dynamic IP address. Domains receive unique IP addresses because as well as a domain name, IP addresses can’t be repeated. In order to avoid repetitions and conflicts, IP addresses are assigned by ICANN.
DNS entries: For a domain to be available, many DNS entries are needed. Entries are divided into four sections: domain name first, protocol type (e.g. IN = internet) second, entry type third, and entry value fourth (e.g. IP address). Moving forward, we’ll show you types of single-entry DNS records.
A record: The A entry deposits the IPv4 address under which the domain is located. They are the most important forms of DNS entries and are used for assigning a webserver to a domain in order for a web browser to call the domain.
AAAA record: Similar to the A record, but the domain is assigned to an IPv6 address.
CNAME record: With a CNAME record (Canonical Name Resource Records), a domain can refer to another domain by containing an alias if other names are assigned.
MX record: MX stands for “mail exchange,” which defines the mail server responsible for the domain. Usually two mail serves are entered for one domain. If the first server is not reachable it automatically attempts to deliver the e-mail to the second server. The mail servers aren’t required to be identical to the server where the respective web space is located, but MX entries must directly refer to A or AAAA entries since CNAME entries aren’t reliable.
NS record: NS records (Name Server Resource Record) are a DNS server’s data set. On the one hand, it defines which name server is responsible for specific zones. On the other hand, it connects single zones to the zone tree (delegation).
PTR record: Pointer Resource Records assign one or more host names to a certain IP address in the DNS. Host names are precise terms for a computer in a network.
SRV record: With Service Resource Records, the DNS can define which IP-based services are offered under the domain or subdomain. They are often used for XMPP, SIP or LDAP protocols and Microsoft Office 365.
TXT record: Text Resource Records enable files to include freely definable text in a DNS zone.
TTL: The TTL (Time To Live) section is part of a DNS entry type and displays how long (in seconds) information is valid. If the time is up, a fresh query is needed. With this, providers’ DNS servers can decide how long their data sets are kept in the cache.
Take a look at this article to learn more about Top Level Domain, Second Level Domain and more.
In part 3, you’ll get to know what’s behind the terms Domain Name Registry, Registrar and Whois.