Thursday, 3 December 2015
Wednesday, 2 December 2015
How DNS resolves DNS query using "Forwarder"???
A DNS server configured to use a forwarder will behave differently than a DNS server that is not configured to use a forwarder. A DNS server configured to use a forwarder behaves as follows:
- When the DNS server receives a query, it attempts to resolve this query using the primary and secondary zones that it hosts and its cache.
- If the query cannot be resolved using this local data, then it will forward the query to the DNS server designated as a forwarder.
- The DNS server will wait briefly for an answer from the forwarder before attempting to contact the DNS servers specified in its root hints.
When a DNS server forwards a query to a forwarder it sends a recursive query to the forwarder. This is different than the iterative query that a DNS server will send to an other DNS server during standard name resolution (name resolution that does not involve a forwarder).
Query using Root hints vs forwarder
Using Root hints
Root hints are DNS resource records stored on a DNS server that list the IP addresses for the DNS root servers
Using Forwarders
A forwarder is a DNS server designated by other internal DNS servers to forward queries for resolving external or offsite DNS domain names
Sunday, 29 November 2015
DNS overview...
What is it?
The Domain Name System (DNS) translates Internet domain and host names to IP addresses.
How does it work?
DNS Namespace (hierarchical structure):
DNS standard name resolution process:
Saturday, 21 November 2015
Friday, 20 November 2015
Linux: creating a self-signed certificate...
A few simple commands to generate a self-signed certificate for your Linux server:
#mkdir -p /etc/ssl/private/#openssl req -x509 -nodes -days 97300 -newkey rsa:2048 -keyout /etc/ssl/private/pure-ftpd.pem -out /etc/ssl/private/pure-ftpd.pem
#chmod 600 /etc/ssl/private/pure-ftpd.pem
General: Understanding load balancing...
Adding two new lines of Internet connections:
Then it will work this way by sharing equal loads between the three ISPs:
If one line cuts off, the remaining two lines will share equal loads again without causing problem. So, the Internet is still up and running.
This is why load balancing is cool. And it will work also with other thing like Apache web server as an example.
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