JN0-106 Junos Configuration Basics Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  The 'apply-groups' statement is used to specify which group(s) should be inherited.

  Why this is correct

  The 'apply-groups' statement is the mechanism that activates configuration-group inheritance at a specific hierarchy level. When included, Junos pulls the named group's statements into the configuration as if they were explicitly defined at that level. It can be placed at multiple levels, enabling selective inheritance, and multiple groups can be listed in a single apply-groups statement for apply-order precedence.

• ✗

  A maximum of 10 groups can be applied to a single configuration statement.

  Why it's wrong here

  Junos imposes no fixed limit of 10 groups per configuration statement; the number of usable groups scales with platform memory and CPU resources. In practice, you can apply many groups, though an excessive number may impact commit performance and readability. The 'maximum of 10' misconception likely stems from examples and training materials that happen to illustrate a small set of groups.

• ✓

  Groups can be nested (i.e., a group can inherit another group).

  Why this is correct

  Configuration groups can be nested by placing an 'apply-groups' statement inside a group definition, causing that group to inherit statements from another group. This creates a layered inheritance hierarchy where a child group builds on a parent's configuration. The parent group's statements are evaluated first, and the child's statements take precedence when both define the same parameter.

• ✓

  They allow a set of configuration statements to be defined once and inherited by multiple sections.

  Why this is correct

  A configuration group defines a reusable set of statements that can be applied to multiple sections of the hierarchy via 'apply-groups', eliminating the need to duplicate identical configuration blocks. This centralizes common settings—such as SNMP, syslog, or user authentication—so changes are made once and automatically inherited everywhere the group is applied. It is the core value proposition of groups: write once, inherit broadly.

• ✗

  Configuration groups do not allow individual statements within the group to be overridden in the main configuration.

  Why it's wrong here

  The main configuration can override individual statements inherited from a group; this override behavior is fundamental to how groups work. Junos uses a precedence scheme where more specific configuration levels take priority over less specific ones, and within the same level, the main configuration beats group values. Additionally, if multiple groups are applied, the first group in the apply-groups list wins over later groups for conflicting statements.