DNS is Domain Name Server, the server used to know the IP address of a host by its host name. In the world of the Internet, computers communicate with one another to identify the IP Address-nya.Namun for humans is not possible to memorize the IP address, the man is more easily memorized words like http://nstars.net or www.google.com. So, DNS function to convert a name that can be read by humans into the IP addresshost concerned to be contacted
The DNS works:
When we are requesting an address, for example http://nstars.net from our host (124.195.3.23), then we will host a local name server contacted to ask where is http://nstars.net com located. ITS name server (124.195.3.2) will search request in the local databasen. Since no, then the name server will contact the root DNS server, who holds the domain for. com
Some list of the Top Level Domain (TLD) that exist today are: com, net, org, biz, info, name, museums, and tv. While Country Code Top Level Domain (ccTLD) is: us, uk, fr, es, de, it, jp, ie, etc..
Root server will tell the IP address of the server DNS from www.facebook.com. Then the local DNS server will contact the DNS server that manages www.facebook.com. Then the DNS server will tell the IP address of www.facebook.com. then requesting with a new host with IP address.
DNS Terminology
1. SOA MNAME – SOA: Start Of Authority
fields that show a master server on the top / root of the zone authority. Only allowed to have one master server per zone authority. Domain example its.ac.id have SOA MNAME ns1.its.ac.id
2.SOA RNAME
SOA RNAME is the email address of the person or organization that is responsible in this zone. The format of this field is different from the usual email format (ie wear a sign'@'). The format used in this field is the mailbox-name.domain.tld. For example itsnet.its.ac.id be equivalent to itsnet@its.ac.id
3. SOA Serial Number
SOA Serial Number is a field that indicates the serial number of the DNS server. This field contains the unsigned 32 bit value ranging from 1 to 4294967295 with the number of maximum increments 2147483647. In the implementation of BIND (Berkeley Internet Name Daemon), this field is defined in 10 digits. The most popular format in naming the serial number is yyyymmddss with yyyy is year, mm is month, dd is the date, and ss is the number of changes made on that day. The value of this field must be changed when there is a change in the zone file. These changes must be done because another server stores information about the zone based on the serial number. During the serial number does not change server, then the data in the cache is also not going to change
4. SOA REFRESH
SOA REFRESH is a field that indicates when the slave server will refresh the zone from the master server. This field in seconds with a value of signed 32 bit. RFC1912 recommends 1200 to 43 200 seconds. 1200 seconds if the data is rapidly changing and 43 200 seconds if data rarely changes.
5. SOA RETRY
SOA Retry is a field that indicates how long the delay time between experiments slave master server if the server is contacting their first contacts failed when the slave master to refresh the cache from the master server. This field in seconds with a value of signed 32 bit. The ideal value depends on state and local network speeds. Usually its value is 180 (two minutes) to 900 (thirteen minutes) or higher.
6. SOA EXPIRE
SOA EXPIRE is a field that indicates how long the zone-data is still authoritative. This field applies only to the slave or secondary server. When this value has expired, then the slave master will contact the master server to read the SOA record in zone and requesting AXFR / IFXR if the serial number changed. If the slave fails to contact the master, the slave will continue to try to contact the master and masihmelayani SOA EXPIRE query until the time runs out. After that the slave will stop serving the query to the contacts to the master server successfully. RFC 1912 recommends 1209600 to 2419200 (2-4 weeks).
7. SOA MINIMUM TTL (Time To Live)
SOA MINIMUM TTL is the default value of TTL (Time To Live) for all records in the zone file. This field in units of seconds. Implementation BIND9 define this field in a negative value.
8. CNAME
CNAME, Canonical Name for Alias is a record describing the primary name for the owner. Ownernya name mentioned in the alias. The format is: CNAME
9. MX
MX is a record that describes the domain mail exchange. The format is as follows: [domain-name] IN MX [Preference] [Exchange], Where: Preference is a 16 bit integer that indicates the preferences of a domain with other domains. The smaller the value the better preferencesnya. Exchange is a domain that will handle the mail exchange for the owner name.
10. A
A is the field that shows the IPv4 address. Name of owner IP address will be equivalent to that defined after record A.
11. PTR
PTR is the domain name pointer, which is a record that points to a specific location in the domain name space
12. AAAA
AAAA is like a record A record that shows the address of the IPv6 address a specific class with 128-bit data format (in accordance with the format bit IPv6).
13. TXT
TXT is a record that shows the text strings, used to handle text that contains a description of a domain. Semantics depends on the domain name where the text was found.