dnsagent
-------
    A tool to monitor DNS resolution times for a set of static domains. The
    domains are :

        |   1 |  google.com  |
        |   2 | facebook.com  |
        |   3 | youtube.com   |
        |   4 | yahoo.com |
        |   5 | live.com    |
        |   6 | wikipedia.org |
        |   7 | baidu.com |
        |   8 | blogger.com   |
        |   9 | msn.com     |
        |   10 | qq.com


        It stores the ping request time series (request time and latency) in a
        mysql database tables.


Database
--------
    The tool uses 'mysql' database to store DNS query related statistics. Tables
    are:

    1. domains: This table is master table for domain names

    Description:

    +-------+--------------+------+-----+---------+----------------+
    | Field | Type         | Null | Key | Default | Extra          |
    +-------+--------------+------+-----+---------+----------------+
    | id    | mediumint(9) | NO   | PRI | NULL    | auto_increment |
    | name  | varchar(500) | NO   | UNI | NULL    |                |
    +-------+--------------+------+-----+---------+----------------+



    2. pings: This table stores time series data (request time, response
        latency)

    Description:

    +-----------+--------------+------+-----+---------+-------+
    | Field     | Type         | Null | Key | Default | Extra |
    +-----------+--------------+------+-----+---------+-------+
    | id        | mediumint(9) | NO   | PRI | 0       |       |
    | request   | bigint(20)   | NO   | PRI | 0       |       |
    | timetaken | bigint(20)   | YES  |     | NULL    |       |
    +-----------+--------------+------+-----+---------+-------+


    Assumption:
        The tool assumes base database  'mysql' present and created on the host.
        In other words, the following command should let you inside the
        database (or prompt you for password):

        mysql -u <user> -p mysql

Usage
------

    Set LD_LIBRARY_PATH to include dynamic library paths (see below for library dependencies)

    Run the tool's executable 'dnsagent' as:

    ./dnsagent -d <database name> -u <database user> -p <database password> [-h <database host>] [-f <frequency in seconds>] [-s]

    Arguments:

        Mandatory:
            -d : Database name where the tool's tables will be created.
            -u : Database user whose credentials will be used to connect to the database.
            -p : Database user password whose credentials will be used to connect to the database.


        Optional:
            -h : Database host (defaulted to 'localhost' if not specified)
            -f : DNS query frequency in seconds.

    Run modes:
        default (query mode): In the default mode, the tool will start pinging the DNS server
                              every 'frequency' seconds.

        stats only: This mode is triggered by the '-s' option. In this mode, the
                    tool uses the stored data in the database to print statistics. It DOES
                    NOT send any DNS query in this mode.


    Summary statistics:
        The tool will print query statistics

            a. when the 'query mode' is interupted (ctrl + c)
                        OR
            b. when ran in 'stats only' mode.


    Examples:

    1. ./dnsagent -d domstats -u root -p password
        This will run the dnsagent in "query mode".

    2. ./dnsagent -d domstats -u root -p password -s
        This will run the tool in "stats only" mode.


Runtime requirements
-------------------
- The tool assumes mysql database being installed on the "host"
- The executable has following external library dependencies:

        libmysqlpp.so.3
        libmysqlclient.so.16
        libldns.so.1
        libstdc++.so.6
        libm.so.6
        libgcc_s.so.1
        libc.so.6
        libpthread.so.0
        libcrypt.so.1
        libnsl.so.1
        libz.so.1
        libcrypto.so.0.9.8
        libdl.so.2



Build Instructions (On **nix systems)
-----------------------------

1. make
    This will build an executable 'dnsagent' in the source directory.

2. make debug
    This will build the executable 'dnsagent' with DEBUG flag turned on.