Saturday 13 April 2013
Friday 22 February 2013
How DNS works
Lets assume I have purchased domain from Tucows registrar or one of its reseller 123-reg.co.uk
domain purchased is www.inderchauhan.com
1. A user types www.inderchauhan.com
2. request is sent to user's DNS
3. Since it is new domain, users DNS is not having cached enteries, so it will contact higher DNS server i.e. root
4. Root (.) will direct to com (there are only 13 root servers..why only 13 ..may be some DNS packet size limitation..please google)
5. All authorized registrars for selling .com domain will receive request about inerchauhan domain
6. tucows will respond via its 123-reg.co.uk reseller
7. 123-reg.co.uk will check his DNS for ns enteries i.e. the authorized DNS server for this domain
8. Now ns server of that domain will be contacted to get server ip on which web site is hosted
9. DNS of that domain will have domain defined in named.conf file as well as zone files (for reverse as well as forward lookup) reverse lookup helps to check ip to name mapping..also helps to know which web sites are hosted on that IP
10. once cached to requester's DNS ..further requests will be handled by it.
Note : Registrar and web hosting company can be same . In this scenario you can use there DNS
Incase you purchased domain from tucows and you want to host your web site to some other ISP or web hosting service provider. You will require to change ns enteries at tucows to web hosting service provide . At the same time web hosting service provider DNS should have all enteries in its zone file (ns,mx,x records).
These can be done by front end tools provided by services providers ..either portal or Cpanel
other tools may be helpful in process
1. www.iplocation.net
2. www.domaintools.com
domain purchased is www.inderchauhan.com
1. A user types www.inderchauhan.com
2. request is sent to user's DNS
3. Since it is new domain, users DNS is not having cached enteries, so it will contact higher DNS server i.e. root
4. Root (.) will direct to com (there are only 13 root servers..why only 13 ..may be some DNS packet size limitation..please google)
5. All authorized registrars for selling .com domain will receive request about inerchauhan domain
6. tucows will respond via its 123-reg.co.uk reseller
7. 123-reg.co.uk will check his DNS for ns enteries i.e. the authorized DNS server for this domain
8. Now ns server of that domain will be contacted to get server ip on which web site is hosted
9. DNS of that domain will have domain defined in named.conf file as well as zone files (for reverse as well as forward lookup) reverse lookup helps to check ip to name mapping..also helps to know which web sites are hosted on that IP
10. once cached to requester's DNS ..further requests will be handled by it.
Note : Registrar and web hosting company can be same . In this scenario you can use there DNS
Incase you purchased domain from tucows and you want to host your web site to some other ISP or web hosting service provider. You will require to change ns enteries at tucows to web hosting service provide . At the same time web hosting service provider DNS should have all enteries in its zone file (ns,mx,x records).
These can be done by front end tools provided by services providers ..either portal or Cpanel
other tools may be helpful in process
1. www.iplocation.net
2. www.domaintools.com
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