Infoblox NIOS-DDI-Expert Practice Exams
Last updated on Oct 22,2026- Exam Code: NIOS-DDI-Expert
- Exam Name: Infoblox Qualified NIOS DDI Expert - INE
- Certification Provider: Infoblox
- Latest update: Oct 22,2026
Question #50
How does an administrator obtain new NIOS releases?
- A . In Grid UI, go to Grid > Software > Download
- B . Contact Infoblox Technical Support for a Software Bundle
- C . Contact the Infoblox Account Manager for a Support Bundle
- D . Download from https://support.infoblox.com
Correct Answer: D
D
Explanation:
Comprehensive and Detailed In-Depth
Obtaining new NIOS software releases follows a standardized process tied to Infoblox’s support infrastructure:
Official Method: New releases (e.g., NIOS 8.6.x) are available for download from the Infoblox Support Portal (https://support.infoblox.com) under the "Downloads" section. Admins log in with valid credentials, select the appliance model, and download the .upgrade file.
Options Analysis:
A: "Grid > Software > Download" isn’t a valid path in Grid Manager. The UI supports uploading and distributing releases (Grid > Upgrade), but not direct downloading. Incorrect.
B: Technical Support can assist with issues or provide files in rare cases (e.g., beta releases), but it’s not the standard method―self-service via the portal is preferred. Incorrect.
C: Account Managers handle sales, not software distribution. "Support Bundle" is also a misnomer― it’s for diagnostics, not upgrades. Incorrect.
D: The support portal is the documented, primary source for NIOS releases, aligning with INE’s focus on Grid upgrade procedures. Correct.
Steps: Download the file, upload it via Grid Manager (Grid > Upgrade > Upload), and initiate the upgrade process.
Practical Example: In an INE lab, you’d download NIOS 8.6.2 from the portal, upload it, and test a Grid-wide upgrade, troubleshooting any distribution failures.
Reference: Infoblox NIOS Administrator Guide C Obtaining Software Releases; INE Course Content:
NIOS DDI Grid Deployment.
D
Explanation:
Comprehensive and Detailed In-Depth
Obtaining new NIOS software releases follows a standardized process tied to Infoblox’s support infrastructure:
Official Method: New releases (e.g., NIOS 8.6.x) are available for download from the Infoblox Support Portal (https://support.infoblox.com) under the "Downloads" section. Admins log in with valid credentials, select the appliance model, and download the .upgrade file.
Options Analysis:
A: "Grid > Software > Download" isn’t a valid path in Grid Manager. The UI supports uploading and distributing releases (Grid > Upgrade), but not direct downloading. Incorrect.
B: Technical Support can assist with issues or provide files in rare cases (e.g., beta releases), but it’s not the standard method―self-service via the portal is preferred. Incorrect.
C: Account Managers handle sales, not software distribution. "Support Bundle" is also a misnomer― it’s for diagnostics, not upgrades. Incorrect.
D: The support portal is the documented, primary source for NIOS releases, aligning with INE’s focus on Grid upgrade procedures. Correct.
Steps: Download the file, upload it via Grid Manager (Grid > Upgrade > Upload), and initiate the upgrade process.
Practical Example: In an INE lab, you’d download NIOS 8.6.2 from the portal, upload it, and test a Grid-wide upgrade, troubleshooting any distribution failures.
Reference: Infoblox NIOS Administrator Guide C Obtaining Software Releases; INE Course Content:
NIOS DDI Grid Deployment.
Question #52
You accidentally deleted several DNS entries from the Grid.
How can you recover from this mistake
with the least service disruption?
- A . Restore the database from the last backup
- B . Promote a GMC to be the new GM
- C . Force HA failover on the GM, if it is an HA pair
- D . Restore the records from the recycle bin
Correct Answer: D
D
Explanation:
Comprehensive and Detailed In-Depth
Accidentally deleting DNS entries (e.g., A records) in NIOS requires a recovery method that minimizes downtime and complexity. Here’s the analysis:
Recycle Bin Feature: NIOS includes a Recycle Bin (Data Management > DNS > Recycle Bin) that temporarily stores deleted objects (e.g., zones, records) unless permanently purged or the bin is disabled. Restoring from here is instantaneous and doesn’t interrupt services.
Options:
A: Restoring from a backup (Grid > Grid Manager > Backup > Restore) replaces the entire database, requiring service restarts and potentially losing post-backup changes. High disruption. Incorrect.
B: Promoting a Grid Master Candidate (GMC) to Grid Master (GM) shifts control but doesn’t recover deleted records―it’s for GM failure, not data loss. Irrelevant. Incorrect.
C: Forcing HA failover on the GM switches active/passive nodes but doesn’t restore data, as both share the same database. No effect. Incorrect.
D: Restoring from the Recycle Bin (select records > Restore) reverts the deletion with no service impact, assuming the bin is enabled (default in NIOS). Correct.
Practical Example: In an INE lab, you’d delete an A record, navigate to the Recycle Bin, restore it, and verify DNS resolution―all without downtime, testing troubleshooting skills.
Caveat: If the Recycle Bin is disabled or entries are purged, backup restoration (A) becomes necessary, but the question implies least disruption, favoring D.
Reference: Infoblox NIOS Administrator Guide C Recycle Bin; INE Course Content: NIOS DDI DNS
Troubleshooting.
D
Explanation:
Comprehensive and Detailed In-Depth
Accidentally deleting DNS entries (e.g., A records) in NIOS requires a recovery method that minimizes downtime and complexity. Here’s the analysis:
Recycle Bin Feature: NIOS includes a Recycle Bin (Data Management > DNS > Recycle Bin) that temporarily stores deleted objects (e.g., zones, records) unless permanently purged or the bin is disabled. Restoring from here is instantaneous and doesn’t interrupt services.
Options:
A: Restoring from a backup (Grid > Grid Manager > Backup > Restore) replaces the entire database, requiring service restarts and potentially losing post-backup changes. High disruption. Incorrect.
B: Promoting a Grid Master Candidate (GMC) to Grid Master (GM) shifts control but doesn’t recover deleted records―it’s for GM failure, not data loss. Irrelevant. Incorrect.
C: Forcing HA failover on the GM switches active/passive nodes but doesn’t restore data, as both share the same database. No effect. Incorrect.
D: Restoring from the Recycle Bin (select records > Restore) reverts the deletion with no service impact, assuming the bin is enabled (default in NIOS). Correct.
Practical Example: In an INE lab, you’d delete an A record, navigate to the Recycle Bin, restore it, and verify DNS resolution―all without downtime, testing troubleshooting skills.
Caveat: If the Recycle Bin is disabled or entries are purged, backup restoration (A) becomes necessary, but the question implies least disruption, favoring D.
Reference: Infoblox NIOS Administrator Guide C Recycle Bin; INE Course Content: NIOS DDI DNS
Troubleshooting.
Question #53
An Infoblox appliance has been used for an evaluation and returned with data still on it. The appliance has an unknown admin password.
What should the administrator use to factory reset the appliance?
- A . Login to the console with the user name "reset" and select the option to Factory Reset
- B . On the console, press F12 to access the local prompt and enter the command "reset"
- C . During boot up press F7 and select Start in Safe Mode
- D . Access the Emergency Prompt at boot up and enter the command "reset all licenses"
Correct Answer: C
C
Explanation:
Comprehensive and Detailed In-Depth
Factory resetting an appliance with an unknown password requires physical access and a specific recovery method. The options provided don’t fully align with NIOS documentation, suggesting a possible error. Let’s evaluate:
Standard Process:
Boot the appliance, interrupt the boot sequence (e.g., via serial console), access an Emergency Prompt or BIOS-like interface, and issue a factory reset command (typically set factory via CLI after recovery login).
Default recovery credentials (e.g., "infoblox/infoblox") may apply if not changed, but an unknown password implies deeper reset.
Options:
A: No "reset" username exists; default is "admin," and no menu offers "Factory Reset." Incorrect.
B: F12 isn’t a documented NIOS boot key―CLI access doesn’t use function keys this way. Incorrect.
C: F7 for Safe Mode isn’t standard, but Safe Mode could allow CLI access to run set factory. Closest plausible option, though not exact. Potentially correct with adjustment.
D: "reset all licenses" only clears licenses, not a full reset, and Emergency Prompt commands are broader (e.g., set factory). Incorrect.
Likely Correct Process: Interrupt boot, access Emergency Prompt (serial console), use recovery credentials or set factory―not perfectly matched here.
Practical Example: In an INE lab, you’d simulate this by booting a test appliance, resetting it via CLI, and reconfiguring it for Grid joining, testing troubleshooting skills.
Reference: Infoblox NIOS Administrator Guide C Factory Reset; INE Course Content: NIOS DDI Grid Troubleshooting.
C
Explanation:
Comprehensive and Detailed In-Depth
Factory resetting an appliance with an unknown password requires physical access and a specific recovery method. The options provided don’t fully align with NIOS documentation, suggesting a possible error. Let’s evaluate:
Standard Process:
Boot the appliance, interrupt the boot sequence (e.g., via serial console), access an Emergency Prompt or BIOS-like interface, and issue a factory reset command (typically set factory via CLI after recovery login).
Default recovery credentials (e.g., "infoblox/infoblox") may apply if not changed, but an unknown password implies deeper reset.
Options:
A: No "reset" username exists; default is "admin," and no menu offers "Factory Reset." Incorrect.
B: F12 isn’t a documented NIOS boot key―CLI access doesn’t use function keys this way. Incorrect.
C: F7 for Safe Mode isn’t standard, but Safe Mode could allow CLI access to run set factory. Closest plausible option, though not exact. Potentially correct with adjustment.
D: "reset all licenses" only clears licenses, not a full reset, and Emergency Prompt commands are broader (e.g., set factory). Incorrect.
Likely Correct Process: Interrupt boot, access Emergency Prompt (serial console), use recovery credentials or set factory―not perfectly matched here.
Practical Example: In an INE lab, you’d simulate this by booting a test appliance, resetting it via CLI, and reconfiguring it for Grid joining, testing troubleshooting skills.
Reference: Infoblox NIOS Administrator Guide C Factory Reset; INE Course Content: NIOS DDI Grid Troubleshooting.
Question #54
What baud rate does the Serial Console use?
- A . 2400 bps
- B . 9600 bps
- C . 39400 bps
- D . 57600 bps
Correct Answer: B
B
Explanation:
Comprehensive and Detailed In-Depth
The serial console on Infoblox appliances provides low-level access for diagnostics:
Default Settings: Per NIOS documentation, the serial port operates at 9600 baud, with 8 data bits, no parity, 1 stop bit (8N1). This is an industry-standard rate for serial terminals, balancing speed and reliability.
Verification: Connecting via a terminal emulator (e.g., PuTTY, minicom) requires matching 9600 bps―mismatched rates garble output, a common troubleshooting issue.
Options:
A (2400): Too slow, used in older systems, not Infoblox. Incorrect.
B (9600): Matches NIOS spec. Correct.
C (39400): Non-standard, likely a typo (38400 is common elsewhere, but not here). Incorrect.
D (57600): Faster rate for modern devices, not Infoblox default. Incorrect.
Practical Example: In an INE lab, you’d set PuTTY to 9600 bps, connect via null modem cable, and view boot logs, troubleshooting a Grid member’s startup.
Reference: Infoblox NIOS Administrator Guide C Serial Console; INE Course Content: NIOS DDI Grid Troubleshooting.
B
Explanation:
Comprehensive and Detailed In-Depth
The serial console on Infoblox appliances provides low-level access for diagnostics:
Default Settings: Per NIOS documentation, the serial port operates at 9600 baud, with 8 data bits, no parity, 1 stop bit (8N1). This is an industry-standard rate for serial terminals, balancing speed and reliability.
Verification: Connecting via a terminal emulator (e.g., PuTTY, minicom) requires matching 9600 bps―mismatched rates garble output, a common troubleshooting issue.
Options:
A (2400): Too slow, used in older systems, not Infoblox. Incorrect.
B (9600): Matches NIOS spec. Correct.
C (39400): Non-standard, likely a typo (38400 is common elsewhere, but not here). Incorrect.
D (57600): Faster rate for modern devices, not Infoblox default. Incorrect.
Practical Example: In an INE lab, you’d set PuTTY to 9600 bps, connect via null modem cable, and view boot logs, troubleshooting a Grid member’s startup.
Reference: Infoblox NIOS Administrator Guide C Serial Console; INE Course Content: NIOS DDI Grid Troubleshooting.
Question #55
An administrator has both Avaya and Cisco VoIP phones that require the same DHCP option.
What can the administrator do with these two different models of phones?
- A . Only one type of device can be online at any given time
- B . Both device types can be online at the same time, but they must be on different subnets
- C . Both device types can be on the same range through the use of separate Option Filters
- D . The administrator must contact the vendors to update the devices to use different DHCP options
Correct Answer: C
C
Explanation:
Comprehensive and Detailed In-Depth
NIOS supports advanced DHCP configuration, including Option Filters, which match client requests based on DHCP options (e.g., Option 60 for Vendor Class Identifier). If Avaya and Cisco VoIP phones require the same DHCP option (e.g., Option 66 for TFTP server), the administrator can use separate
Option Filters to distinguish the devices by their unique identifiers (like Vendor Class IDs: "Avaya" vs. "Cisco") and assign them IPs from the same range with the shared option. This allows both device types to coexist on the same subnet and range, eliminating the need for segregation (Option B) or vendor intervention (Option D).
Option A is overly restrictive and incorrect. This is a practical DHCP troubleshooting scenario in the INE course.
Reference: Infoblox NIOS Administrator Guide C DHCP Option Filters; INE Course Content: NIOS DDI DHCP Troubleshooting.
C
Explanation:
Comprehensive and Detailed In-Depth
NIOS supports advanced DHCP configuration, including Option Filters, which match client requests based on DHCP options (e.g., Option 60 for Vendor Class Identifier). If Avaya and Cisco VoIP phones require the same DHCP option (e.g., Option 66 for TFTP server), the administrator can use separate
Option Filters to distinguish the devices by their unique identifiers (like Vendor Class IDs: "Avaya" vs. "Cisco") and assign them IPs from the same range with the shared option. This allows both device types to coexist on the same subnet and range, eliminating the need for segregation (Option B) or vendor intervention (Option D).
Option A is overly restrictive and incorrect. This is a practical DHCP troubleshooting scenario in the INE course.
Reference: Infoblox NIOS Administrator Guide C DHCP Option Filters; INE Course Content: NIOS DDI DHCP Troubleshooting.
Question #56
Which action can an administrator safely perform during an upgrade?
- A . Update DNS views
- B . Modify Member DHCP properties
- C . Setting time zone for a Grid Member
- D . None of the above
Correct Answer: C
C
Explanation:
Comprehensive and Detailed In-Depth
During a NIOS software upgrade (Grid > Upgrade), the Grid enters a sensitive state where certain actions risk instability.
Let’s evaluate:
Upgrade Phases: Upload, Distribute, Test, Upgrade. Members reboot and sync, requiring database consistency.
Options:
A: Updating DNS views modifies the database, which could conflict with the upgrade’s database sync or cause service interruptions. Unsafe.
B: Changing DHCP properties (e.g., ranges) alters live configurations, risking lease sync issues during member reboots. Unsafe.
C: Setting the time zone (Grid > Members > Edit > Basic) is a non-service-affecting change, stored locally and applied post-reboot. Safe during upgrades, as it doesn’t impact DNS/DHCP/Grid data. Correct.
D: Incorrect, as C is a viable safe action.
Practical Example: In an INE lab, you’d adjust a member’s time zone during an upgrade to align logs, troubleshooting without disrupting the process.
Reference: Infoblox NIOS Administrator Guide C Upgrade Best Practices; INE Course Content: NIOS DDI Grid Deployment.
C
Explanation:
Comprehensive and Detailed In-Depth
During a NIOS software upgrade (Grid > Upgrade), the Grid enters a sensitive state where certain actions risk instability.
Let’s evaluate:
Upgrade Phases: Upload, Distribute, Test, Upgrade. Members reboot and sync, requiring database consistency.
Options:
A: Updating DNS views modifies the database, which could conflict with the upgrade’s database sync or cause service interruptions. Unsafe.
B: Changing DHCP properties (e.g., ranges) alters live configurations, risking lease sync issues during member reboots. Unsafe.
C: Setting the time zone (Grid > Members > Edit > Basic) is a non-service-affecting change, stored locally and applied post-reboot. Safe during upgrades, as it doesn’t impact DNS/DHCP/Grid data. Correct.
D: Incorrect, as C is a viable safe action.
Practical Example: In an INE lab, you’d adjust a member’s time zone during an upgrade to align logs, troubleshooting without disrupting the process.
Reference: Infoblox NIOS Administrator Guide C Upgrade Best Practices; INE Course Content: NIOS DDI Grid Deployment.
Question #57
What types of permissions can be assigned to a Group or Role in NIOS? (Select all that apply.)
- A . Global permissions
- B . Object permissions
- C . Grid permissions
- D . Member permissions
Correct Answer: A, B, C
A, B, C
Explanation:
Comprehensive and Detailed In-Depth
NIOS uses a granular permission model for admin groups/roles (Administration > Administrators).
Here’s what applies:
A (Global Permissions): Broad privileges across all objects (e.g., "All DNS Zones" read/write). Applies to groups/roles for universal access. Correct.
B (Object Permissions): Specific to individual objects (e.g., read-only on "zone1.example.com"). Assignable to groups/roles for fine control. Correct.
C (Grid Permissions): Control Grid-wide settings (e.g., backup, upgrade permissions). Assignable to groups/roles, distinct from member-specific rights. Correct.
D (Member Permissions): Permissions are tied to Grid members (e.g., restart services on "Member1"), but NIOS documentation classifies these under object or Grid permissions, not a separate "Member" category. Incorrect in this context.
Setup: In Grid Manager, you assign these via group/role properties, selecting scopes (global, object-specific, Grid-level).
Practical Example: In an INE lab, you’d assign a group global DNS write access and Grid backup rights, testing restricted troubleshooting scenarios.
Reference: Infoblox NIOS Administrator Guide C Permissions; INE Course Objective: NIOS DDI Grid Deployment.
A, B, C
Explanation:
Comprehensive and Detailed In-Depth
NIOS uses a granular permission model for admin groups/roles (Administration > Administrators).
Here’s what applies:
A (Global Permissions): Broad privileges across all objects (e.g., "All DNS Zones" read/write). Applies to groups/roles for universal access. Correct.
B (Object Permissions): Specific to individual objects (e.g., read-only on "zone1.example.com"). Assignable to groups/roles for fine control. Correct.
C (Grid Permissions): Control Grid-wide settings (e.g., backup, upgrade permissions). Assignable to groups/roles, distinct from member-specific rights. Correct.
D (Member Permissions): Permissions are tied to Grid members (e.g., restart services on "Member1"), but NIOS documentation classifies these under object or Grid permissions, not a separate "Member" category. Incorrect in this context.
Setup: In Grid Manager, you assign these via group/role properties, selecting scopes (global, object-specific, Grid-level).
Practical Example: In an INE lab, you’d assign a group global DNS write access and Grid backup rights, testing restricted troubleshooting scenarios.
Reference: Infoblox NIOS Administrator Guide C Permissions; INE Course Objective: NIOS DDI Grid Deployment.
Question #58
When viewing NTP statistics in NIOS CLI, you notice an entry has the asterisk symbol () next to it.
What does the asterisk symbol () signify?
- A . It means this NTP server is unreachable
- B . It means the Member is synchronized to this NTP server
- C . It means this NTP server is offline
- D . It means the NTP service is disabled for the Member
Correct Answer: B
B
Explanation:
Comprehensive and Detailed In-Depth
NTP (Network Time Protocol) synchronization is critical for Grid operations, and NIOS CLI provides status via show ntp:
Output Format: Lists NTP servers with symbols:
*: The server the member is currently synchronized to (stratum and offset shown).
+: Candidate server (reachable but not primary).
-: Unreachable or rejected server.
Asterisk Meaning: Indicates the active sync source, ensuring time consistency across the Grid.
Options:
A: Unreachable servers get a “-” or no symbol, not “*”. Incorrect.
B: Matches NTP convention and NIOS behavior―synchronized server. Correct.
C: Offline servers don’t sync and lack “*”. Incorrect.
D: Disabled NTP would prevent stats display, not mark a server. Incorrect.
Practical Example: In an INE lab, you’d run show ntp, see “*pool.ntp.org,” and troubleshoot time drift if the asterisk shifts, testing Grid stability.
Reference: Infoblox NIOS CLI Reference Guide C NTP Commands; INE Course Content: NIOS DDI Grid Troubleshooting.
B
Explanation:
Comprehensive and Detailed In-Depth
NTP (Network Time Protocol) synchronization is critical for Grid operations, and NIOS CLI provides status via show ntp:
Output Format: Lists NTP servers with symbols:
*: The server the member is currently synchronized to (stratum and offset shown).
+: Candidate server (reachable but not primary).
-: Unreachable or rejected server.
Asterisk Meaning: Indicates the active sync source, ensuring time consistency across the Grid.
Options:
A: Unreachable servers get a “-” or no symbol, not “*”. Incorrect.
B: Matches NTP convention and NIOS behavior―synchronized server. Correct.
C: Offline servers don’t sync and lack “*”. Incorrect.
D: Disabled NTP would prevent stats display, not mark a server. Incorrect.
Practical Example: In an INE lab, you’d run show ntp, see “*pool.ntp.org,” and troubleshoot time drift if the asterisk shifts, testing Grid stability.
Reference: Infoblox NIOS CLI Reference Guide C NTP Commands; INE Course Content: NIOS DDI Grid Troubleshooting.
Question #59
The Grid is comprised of all single members.
Which member will upgrade first?
- A . You can choose which member upgrades first
- B . The Grid Master upgrades first
- C . The Reporting server upgrades first
- D . The Grid Master Candidate upgrades first
Correct Answer: A
A
Explanation:
Comprehensive and Detailed In-Depth
Upgrading a Grid of single members (no HA pairs):
A: Admins define Upgrade Groups or schedules (Grid > Upgrade), choosing the order (e.g., “Member1 first”). Correct.
B: GM typically upgrades last by default to maintain control, but this can be overridden. Incorrect.
C: Reporting server (if present) has no priority―user-defined. Incorrect.
D: GMC upgrades only if promoted, not inherently first. Incorrect.
Practical Example: In an INE lab, schedule Member2 first, test upgrade, and troubleshoot sequence issues.
Reference: Infoblox NIOS Administrator Guide C Upgrade Scheduling; INE Course Content: NIOS DDI Grid Deployment.
A
Explanation:
Comprehensive and Detailed In-Depth
Upgrading a Grid of single members (no HA pairs):
A: Admins define Upgrade Groups or schedules (Grid > Upgrade), choosing the order (e.g., “Member1 first”). Correct.
B: GM typically upgrades last by default to maintain control, but this can be overridden. Incorrect.
C: Reporting server (if present) has no priority―user-defined. Incorrect.
D: GMC upgrades only if promoted, not inherently first. Incorrect.
Practical Example: In an INE lab, schedule Member2 first, test upgrade, and troubleshoot sequence issues.
Reference: Infoblox NIOS Administrator Guide C Upgrade Scheduling; INE Course Content: NIOS DDI Grid Deployment.
Question #60
A customer has the following Grid: Grid Master HA pair, three HA Grid Members, one single Grid Member. The customer has defined custom Upgrade Groups based on the physical location of the appliances.
After the administrator clicks Upgrade, which node will go through the upgrade process first?
- A . All of the Member passive nodes
- B . Grid Master active node
- C . Grid Master passive node
- D . Depends on the configuration of Upgrade Groups
Correct Answer: D
D
Explanation:
Comprehensive and Detailed In-Depth
In NIOS, the upgrade process for a Grid can be customized using Upgrade Groups, which allow administrators to define the order and timing of upgrades for Grid members based on criteria like location or role. By default, the Grid Master (active node) upgrades last to ensure continuity, and passive nodes in HA pairs often upgrade before active nodes. However, when custom Upgrade Groups are defined (as in this scenario, based on physical location), the upgrade sequence follows the administrator’s configuration rather than a fixed rule. Thus, the first node to upgrade depends entirely on how the Upgrade Groups are prioritized in the upgrade schedule. This flexibility is a focus of the INE course’s Grid deployment section.
Reference: Infoblox NIOS Administrator Guide C Software Upgrades; INE Course Objective: NIOS DDI Grid Deployment.
D
Explanation:
Comprehensive and Detailed In-Depth
In NIOS, the upgrade process for a Grid can be customized using Upgrade Groups, which allow administrators to define the order and timing of upgrades for Grid members based on criteria like location or role. By default, the Grid Master (active node) upgrades last to ensure continuity, and passive nodes in HA pairs often upgrade before active nodes. However, when custom Upgrade Groups are defined (as in this scenario, based on physical location), the upgrade sequence follows the administrator’s configuration rather than a fixed rule. Thus, the first node to upgrade depends entirely on how the Upgrade Groups are prioritized in the upgrade schedule. This flexibility is a focus of the INE course’s Grid deployment section.
Reference: Infoblox NIOS Administrator Guide C Software Upgrades; INE Course Objective: NIOS DDI Grid Deployment.