Appendix D: Answer Key

Chapter 1: Course Introduction

This chapter contains no review questions.

Chapter 2: Junos Operating System Fundamentals

1.

The Junos OS is compartmentalized into multiple software processes. Each process runs in its own protected memory space, ensuring that one process cannot directly interfere with another. This modularity also ensures that new features can be added with less likelihood of breaking current functionality.

2.

The primary functions of the control plane are to maintain routing intelligence, control and monitor the chassis, and manage the PFE. The primary functions of the forwarding plane are to forward packets and to implement advanced services.

3.

Transit traffic is forwarded through the PFE on platforms running the Junos OS, based on the forwarding table installed on the PFE. Exception traffic is processed locally by the platform running the Junos OS by either the PFE or the RE depending on the type of traffic. Host-bound packets, such as protocol and management traffic, are passed directly to the RE for processing, while traffic requiring ICMP error message responses is typically handled by the PFE.

4.

Platform families that run the Junos OS include ACX Series, LN Series, J Series, M Series, MX Series, PTX Series, T Series, EX Series, QFX Series, and SRX Series.

Chapter 3: User Interface Options

1.

Two primary modes exist within the Junos OS: the operational mode and the configuration mode. A third mode also exists in the form of the FreeBSD shell.

2.

You use the operational mode to monitor and troubleshoot the software, network connectivity, and hardware. You use the configuration mode to configure a device running the Junos OS, including interfaces, protocols, user access, and system hardware.

3.

You use the Spacebar to complete a command and the Tab key to complete a variable. 4.

The top command is the quickest method of returning to the top of the hierarchy. 5.

The active configuration has been committed and is in use, whereas the candidate configuration is not active until you perform a commit operation.

6.

The show | compare command displays the differences between the current active and candidate configurations.

Chapter 4: Initial Configuration

1.

Use the cli command at the shell prompt to enter operational mode. 2.

The root authentication is the only required parameter during the initial configuration. 3.

As always, you must issue a commit for any configuration changes to take effect. 4.

Some examples of logical interface properties you might configure include the protocol family (such as inet, inet6, iso, mpls, or ethernet-switching), addresses, and virtual circuit identifiers (such as VPI, VCI, DLCI, and VLAN tag).

Chapter 5: Secondary System Configuration

1.

Users can be authenticated using the local password database, RADIUS authentication, and TACACS+ authentication.

2.

The messages log is the primary syslog file, and is stored in /var/log directory. Use the show log messages command to view the messages log.

3.

Configuration archival allows for disaster recovery in situations where a system storage device becomes unusable. Archiving configurations can also be a useful part of a company’s configuration management policy.

4.

An SNMP trap is an agent-initiated notification of network events relative to the sending agent.

Chapter 6: Operational Monitoring and Maintenance

1.

The primary method for monitoring devices running the Junos OS is the CLI, which includes operational show and monitor commands. Some secondary methods include J-Web, SNMP, hardware LEDs, and front-panel displays or LCDs.

2.

Use the CLI monitor interface or monitor interface traffic commands to view interface usage in real time.

3.

Use the CLI monitor traffic interface command to perform a packet capture. 4.

You must first download the Junos image for your respective platform from the Juniper Networks download site. The install package can be copied to the device running the Junos OS directly (recommended directory is /var/tmp) or you can copy the image to a server that is reachable through FTP or SCP from the device being upgraded. You then perform the upgrade using the CLI request system software add command. You can monitor the upgrade process through a console connection and verify the Junos OS Release using the CLI show version command.