Config elements in JMeter are used to configure or modify the sampler requests made to the server. These elements are added at the same or higher level of the samplers they want to configure.How to add an Config elements-
The CSV Data Set Config is used to read data from CSV file, put the data into variable(s) and then use the variable(s) in the sampler requests. Check our tutorial on Parameterization in JMeter for details.
The HTTP Cache manager is used in test scripts to add the Caching functionalties of web applications. This element is just required to be added at same level or higher than the sampler request where caching functionality is required.
The HTTP Cookie manager is required to for session handling by providing functionality of storing and sending of cookies.
As the name suggests, the User Defined Variable config element is used to create variables with a value (key-value pairs) that are used across the test script.
The random variable config element is used to generate random numeric values within a range of specified minimum and maximum values.
The counter config element is used to create a variable that gets increamented by a specified value in each iteration within a range of minimum and maximum values.
JDBC Connection Configuration is used with JDBC request sampler to create JDBC connection settings.
The FTP request defaults are used to create default settings while testing FTP servers.
The DNS Cache Manager is used while testing applications behind the load balancers.
The HTTP Authorization Manager is used for testing applications requiring multiple logins for ensuring authorization.
The HTTP Request Defaults config element is used for setting default values for HTTP requests.
The HTTP Header Manager is used to override the HTTP request headers.
The Java request defaults config elements is used to specify default values for Java Request sampler.
The Keystore Configuration config element is used to configure the loading of keystores.
The logic Config element is used to create default credentials for the samplers using username and password in their setup
The LDAP request defaults are used to create default settings while testing LDAP servers.
The LDAP extended request defaults are used to create default settings for LDAP Extended Request samplers.
The TCP Sampler Config is used for creating default settings for TCP Sampler.
The simple config element is used to create key-value pairs that can be used across the test script.