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This section describes DHCP properties that apply to both IPv4 and IPv6. It includes the following sections:

Configuring UTF-8 Encoding for Hostnames

When you configure the appliance as a DHCP server, the appliance supports UTF-8 encoding of hostnames that are encoded with Microsoft Windows code pages. You can configure the DHCP services on the appliance to convert these client hostnames to UTF-8 characters. The appliance stores the UTF-8 encoded hostnames in the database. If you also configure the DHCP services on the appliance to perform DDNS updates, the appliance sends the UTF-8 encoded host names in the DDNS updates. You can configure the UTF-8 encoding of host names at the Grid DHCP service and member DHCP service levels. For information on UTF-8 encoding, see Printing from Grid Manager.
The appliance displays the host names in their original characters in the following:

  • DHCP lease history
  • DHCP lease details
  • IP address management
  • Syslog
  • Audit log

To configure UTF-8 encoding for hostnames:

  1. Grid: From the Data Management tab, select the DHCP tab, and then select Grid DHCP Properties from the Toolbar.
    Member: From the Data Management tab, select the DHCP tab -> Members tab -> Members -> member check box, and then click the Edit icon.
  2. In the DHCP Properties editor, select the General Basic tab and complete the following:
    • IPv4 Properties
      • Microsoft Clients Code Page: From the drop-down list, select the code page with which the host names are encoded when the appliance converts the Microsoft code page encoded host names to UTF-8 characters.
    • IPv6 Properties
      • Microsoft Clients Code Page: From the drop-down list, select the code page with which the host names are encoded when the appliance converts the Microsoft code page encoded host names to UTF-8 characters.
  3. Save the configuration and click Restart if it appears at the top of the screen.

Associating Networks with Zones

You can associate IPv4 and IPv6 networks with DNS zones to limit the zones that admins can use when they create DNS records for IP addresses in the networks. When a network is associated with one or more zones and an admin creates a DNS record for one of its IP addresses, Grid Manager allows the admin to create the DNS record in the associated zones only. For example, if you associate the 10.1.0.0/16 network with the corpxyz.com zone, admins are allowed to create DNS records in the corpxyz.com zone only for IP addresses in the 10.1.0.0/16 network; or if you associate the 2001:db8:1::/48 network with the corp200.com zone, admins are allowed to create DNS records in the corp200.com zone only for IP addresses in the 2001:db8:1::/48 network.
This feature applies to A, AAAA and host records only. It does not apply to records in a shared record group. If you are creating a host record with multiple IP addresses in different networks, the networks must be associated with the zone of the host record.
If a network is not associated with a zone, admins can create DNS records for its IP addresses only in zones with no network associations as well.
You can associate a network with any authoritative zone whose primary server is a Grid member or a Microsoft server, or is unassigned. You cannot associate networks with zones that have external primary servers.
You can associate a network with multiple zones, and associate a zone with more than one network. You can associate IPv4 and IPv6 network containers and networks with zones. When you associate a network container with zones, its networks inherit the zone associations. You can override the zone associations at the network level.
If you split a network, the resulting subnets inherit the zone associations. If you join networks, the resulting network retains the zone associations of the network that you selected when you performed the join operation. You can override the inherited zone associations of individual networks. Subzones do not inherit the network associations of their parent zones.
When you import data into a zone that is associated with a list of networks, the imported A, AAAA and host records must have IP addresses in the associated networks. Grid Manager does not allow you to import A, AAAA and host records with IP addresses in unassociated networks.
When you associate a network with a zone, the DNS records created before the association are not affected. But if you edit an A, AAAA or host record after the association, Grid Manager does not allow you to save the record if its IP address is not in an associated network.
To associate an IPv4 or IPv6 network with a zone:

  1. From the Data Management tab, select the DHCP tab -> Networks tab -> Networks -> network check box, and then click the Edit icon.
  2. In the DHCP Network editor, click Toggle Advanced Mode if the editor is in basic mode.
  3. When the additional tabs appear, click the Advanced subtab of the General tab.
  4. Click the Add icon and select the zone you want to associate with the network.
    • Optionally, select a default zone. When you create or edit an A, AAAA or host record from a network in the IPAM tab, Grid Manager automatically selects the default zone that is assigned to the network.

5. Save the configuration or click the Schedule icon at the top of the wizard to schedule this task. In the Schedule Change panel, enter a date, time, and time zone. For information, see Scheduling Tasks.

Viewing the Networks Associated with a Zone

You can view the IPv4 or IPv6 networks associated with a zone from the zone editor. The tab to display network associations in zone editors is visible only if the primary server is a Grid member, a Microsoft server, or unassigned.
To view the network associations of a zone:

  1. From the Data Management tab, select the DNS tab -> Zones tab -> zone check box, and then click the Edit icon.
  2. In the Authoritative Zone editor, click Toggle Advanced Mode if the editor is in basic mode.
  3. When the additional tabs appear, click the Advanced subtab of the General tab.

The Network Associations table lists the networks and their corresponding comments. You cannot change the network associations in this editor. Navigate to the DHCP Network editor of the network, to change the zone associations.

Keeping Leases in Deleted IPv4 and IPv6 Networks and Ranges

You can configure the DHCP server to store leases in a deleted DHCP range for up to one week after the leases expire. When you add a new DHCP range that includes the IP addresses of these leases or assign the DHCP range to another member within the Grid, the appliance automatically restores the active leases. You can configure this feature for the Grid, and override the configuration for members, networks, and DHCP ranges.
To keep active leases in a deleted DHCP range:

  1. Grid: From the Data Management tab, select the DHCP tab, and then click Grid DHCP Properties from the Toolbar.
    Member: From the Data Management tab, select the DHCP tab -> Members tab -> Members -> member check box, and then click the Edit icon.
    Network: From the Data Management tab, select the DHCP tab -> Networks tab -> Networks -> network check box, and then click the Edit icon.
    Network Container: From the Data Management tab, select the IPAM tab -> network_container check box, and then click the Edit icon.
    Range: From the Data Management tab, select the DHCP tab -> Networks tab -> Networks -> network -> range check box, and then click the Edit icon.
  2. In the DHCP Properties editor of the Grid or member, click Toggle Advanced Mode if the editor is in basic mode, and then click the General tab -> Advanced tab. In the Network editor or Range editor, click Toggle Advanced Mode if the editor is in basic mode, and then click IPv4DHCPOptions -> Advanced or IPv6 DHCP Options -> Advanced. Complete the following:
    • IPv4 Properties
      • Lease Deletion: When you select Keep leases from deleted range until one week after expiration and delete a DHCP range with active leases, the appliance stores these leases for up to one week after they expire.
    • IPv6 Properties
      • Lease Deletion: When you select Keep leases from deleted range until one week after expiration and delete a DHCP range with active leases, the appliance stores these leases for up to one week after they expire.
  3. Save the configuration and click Restart if it appears at the top of the screen.

Configuring Fixed Address Leases For Display

You can configure the DHCP server to capture the hostname and lease time of a fixed address when you assign an IPv4 or IPv6 fixed address to a client. The appliance displays the hostname, and the start and end time of each fixed address lease in the Current Leases panel in Grid Manager.
You can set this at the Grid level only for IPv4 and IPv6 leases.

  1. From the Data Management tab, select the DHCP tab, and then click Grid DHCP Properties from the Toolbar.
  2. In the Grid DHCP Properties editor, click Toggle Advanced Mode if the editor is in basic mode. When the additional tabs appear, click the General tab -> Advanced tab and complete the following:
    • IPv4 Properties
      • Fixed Address Lease: Select Capture hostname and lease time when assigning Fixed Addresses. The appliance displays the host name, and the start and end time of each fixed address lease in the Current Leases panel. If there are multiple records (A, host, and lease) for the IP address, it also displays the information for the records. This option is available in the Grid Properties editor only.)
    • IPv6 Properties
      • Fixed Address Lease: Select Capture hostname and lease time when assigning Fixed Addresses. The appliance displays the host name, and the start and end time of each fixed address lease in the Current Leases panel. If there are multiple records (AAAA, host, and lease) for the IP address, it also displays the information for the records. This option is available in the Grid Properties editor only.)
  3. Save the configuration.

Scavenging Leases

The accumulation of free and backup DHCPv4 leases; and free, expired, and released DHCPv6 leases results in unnecessary growth of database objects. The DHCP lease scavenging feature enables member DHCP servers to automatically delete free and backup IPv4 leases; and free, expired, and released IPv6 leases that remain in the database beyond the specified period of time, thus reducing the number of database objects.
When you enable this feature for DHCPv4 leases, the appliance permanently deletes the free and backup IPv4 leases, and you can no longer view or retrieve the lease information. This option can be enabled globally at the Grid level, and more specifically for a member, shared network, network, network container, DHCP range, network template, DHCP range template.
When you enable this feature for DHCPv6 leases, the appliance permanently deletes the free, expired, and released IPv6 leases, and you can no longer view or retrieve the lease information. This option can be enabled at the Grid level, and overridden at the member level.
The period of time that you specify is the duration after the expiration date of a lease, not its release date. For example, you specify a time period of 5 days when you enable this feature. If the lease time of an IP address is 10 days, but the lease is released after five days, the appliance still deletes the lease from the database after 15 days because the IP address has been leased.


Note: If you plan to enable this feature after upgrading from a previous NIOS version, Infoblox recommends that you enable it during off-peak hours, as it may impact DHCP services.


To enable scavenging of IPv4 and IPv6 leases:

  1. Grid: From the Data Management tab, select the DHCP tab, and then click Grid DHCP Properties from the Toolbar.
    Member: From the Data Management tab, select the DHCP tab -> Members tab -> Members -> member check box, and then click the Edit icon.
    Network: From the Data Management tab, select the DHCP tab -> Networks tab -> Networks -> network check box, and then click the Edit icon. This is applicable for IPv4 lease scavenging only.
    Network Container: From the Data Management tab, select the IPAM tab -> network_container check box, and then click the Edit icon. This is applicable for IPv4 lease scavenging only.
    DHCP Range: From the Data Management tab, select the DHCP tab -> Networks tab -> Networks -> network -> addr_range check box, and then click the Edit icon. This is applicable for IPv4 lease scavenging only.
  2. In the editor, click Toggle Advanced Mode if the editor is in basic mode, and then click the General tab -> Advanced tab.

In the Network editor for IPv4 lease scavenging, click Toggle Advanced Mode if the editor is in basic mode, and then click IPv4 DHCP Options -> Advanced.
Complete the following:

    • IPv4 Properties
      • Lease Scavenging: This is disabled by default. Select the Scavenge free and backup leases after check box and specify the number of days or weeks that free and backup IPv4 leases remain in the database before they are automatically deleted. This can be set for the Grid, member, network, and network container.
    • IPv6 Properties
      • Lease Scavenging: This is disabled by default. Select the Scavenge free, expired and released leases after check box and specify the number of hours, days, or weeks that free, expired, and released IPv6 leases remain in the database before they are automatically deleted. The minimum is 6 hours and the maximum is 180 days. The default is one week. This can be set at the Grid and member level.

     3. Save the configuration.

DHCPv6 Lease Affinity

DHCPv6 ranges are usually large and the DHCPv6 server randomly selects a new lease each time a client requests for a lease. The client can use the lease until it expires. After its expiration, the lease stays in the database with an expired state. These expired leases eventually lead to the increase in the number of database objects, because the probability of expired IPv6 leases getting reused is low.
Infoblox provides a DHCPv6 lease affinity feature that allows you to reuse expired IPv6 leases for DHCP clients. When you enable this feature, the DHCPv6 server automatically renews the expired leases. A DHCP client can retrieve the same lease from the DHCPv6 server after it expires and retains the same IP address. This feature helps reduce the amount of IPv6 leases in the database as the DHCP server issues the same lease multiple times for the same client.
The appliance ignores expired leases that are older than the specified period. Such leases are scavenged. Note that the grace period you define for lease scavenging is applicable for DHCPv6 lease affinity also. The minimum time period is six hours, maximum is 180 days and the default is set to seven days. For more information about scavenging leases, see Scavenging Leases.


Note: The DHCPv6 server offers the same lease for a DHCP client, identified by DUID, after the lease expires and before the end of the grace period. The appliance removes the expired leases that are older than the grace period from the database.


DHCPv6 lease affinity and DHCPv6 lease scavenging are complementary features. For example, consider a scenario in which a visiting user gets an IPv6 lease that is retained for days, weeks, or months depending on the needs and then the user leaves. If the user returns and the lease is still within the grace period, the user gets the same IPv6 lease. This is lease affinity. When the user leaves, the IPv6 lease becomes inactive. This lease is scavenged after the grace period.
Note the following about DHCPv6 lease affinity:

  • It does not consider expired leases that are older than the grace period.
  • It ignores expired leases that do not match known ranges.
  • If no existing lease is found, then the DHCPv6 server finds a suitable expired lease that is not older than the grace period, which matches the client DUID and range configuration.
  • The impact of the feature on the performance depends on the amount of expired DHCPv6 leases.
  • When you activate the feature at the Grid level, it affects all underlying layers of inheritance.
  • You cannot enable DHCPv6 lease affinity at the Grid and member levels during a scheduled full upgrade.
  • DHCPv6 lease affinity remembers only permanent addresses and does not remember temporary addresses and prefix delegations.
  • If the DHCPv6 range is out of available addresses when you enable DHCPv6 lease affinity, then the DHCP server tries to reuse the best abandoned lease, which indicates the lease that was abandoned longest time ago. If there are no such leases in the pool, the DHCP server reuses the best expired lease, which indicates the lease that expired longest time ago. This means that the expired lease becomes active and it is associated with the new client while the DHCP server removes any previous associations of the corresponding lease. Note that this happens only when the DHCPv6 range does not have any available addresses and there are no suitable abandoned leases.

To enable DHCPv6 lease affinity:

  1. Grid: From the Data Management tab, select the DHCP tab, and then click Grid DHCP Properties from the Toolbar.
    Member: From the Data Management tab, select the DHCP tab -> Members tab -> Members -> member check box, and then click the Edit icon.
  2. In the editor, click Toggle Advanced Mode if the editor is in basic mode, and then click the General tab -> Advanced tab.

Complete the following:

    • IPv6 Properties
      • Lease Scavenging
        • Remember client association for expired members: This is disabled by default. Select the check box to remember and reuse expired IPv6 leases that are associated with DHCP clients. You can select this check box only when you select the Scavenge free, expired and released leases after check box. This can be set at the Grid and member levels.

Note: The appliance stores the leases, which are either deleted or removed, in the recycle bin. These leases then become free and are automatically dissociated from their clients. For example, if you delete a range accidentally and restore it again, the IPv6 leases associated with the respective range are no longer associated with the same set of clients.


    3. Save the configuration.


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