The DNS protocol translates names, such as “www.teamtreehouse.com” in to IP addresses.
Domain Names
subdomain.domainname.tld
Different parts of a domain name mean different things and are looked-up different ways.
Domain names must be formatted a certain way in order to be valid.
Top Level Domain (TLD )
A famous example of a Top Level Domain is ".com".
Types of TLDs
- Generic TLDs
- Country-code TLDs
- Infrastructure TLDs
Root Servers
The DNS root servers keep track of the root zone, and keep track of all of the top level domains such as .com, .org, and more.
Root Zone file is the authoritative list of DNS servers for all TLDs. Meaning, it contains information for all TLDs in the zone.
There are 13 total root servers located throughout the world.
Without the root servers, there would be no internet.
Name Servers
Name servers are the first hop after the root servers,
DNS name servers hold the information about a given domain. Name servers also provide answers to your DNS queries.
There are 2 different kinds of name servers:
- Master: The master name server stores the original copies of records.
- Slave: The slave name server gets copies of the records.
Domain Name Formatting Rules
- Type Number
There are currently 326 different top level domains. - Reading Domains
Domain names are read right to left: TLD, domain, and subdomain(s). - Domain Levels
There can be up to 127 levels of a domain name. - Length
The full domain name may be up to 253 character* and must use the ASCII character set. - LDH rul
The domain name must follow the (i.e. Letters, Digits, Hyphens).
This is commonly referred to when naming domains and subdomains. - Name Start
Domain names cannot start or end with a hyphen.
Time To Live (TTL)
When changes are made to a domain name, they are not always immediately picked up because of the Time to Live (TTL) property.
TTL This specifies the number of seconds in which information should be updated. Low TTL means less time. High TTL means longer time.