Secondary zones and stub zones

Installing an HCP SAIN System - Final On-Site Setup

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In the DNS, you configure each HCP domain as a secondary zone or as a stub zone. A DNS server in which a given HCP domain is configured as a secondary zone maintains a full copy of the HCP DNS information for that domain and can, therefore, satisfy requests for resolution of the HCP domain name by itself. You might use secondary zones, for example, if the firewall that HCP sits behind is configured to allow client requests for DNS name resolution to go only to a corporate DNS server.

A DNS server in which a given HCP domain is configured as a stub zone gets only partial DNS information for that domain from HCP. Stub zones minimize zone replication and are less resource intensive for the DNS server.

If you enable hidden primary or notify for a network, the HCP domain for that network must be configured as a secondary zone, not a stub zone, on each DNS server specified in the network configuration.

Secondary zone and stub zone definitions are basically the same. Each definition lists the IP addresses of primary name servers for a domain but does not include individual records for those servers. Those records are stored on the primary name servers themselves. The DNS servers get the individual name server records from the primary name servers listed in the zone definition.

For each network defined in HCP, HCP automatically generates name server records for all storage nodes that have IP addresses in that network. Each of those storage nodes stores a copy of these records, thereby making each storage node eligible to be a primary name server for the applicable domain.

Before HCP can accept client requests that identify the system by a domain name, you need to register some or all of the eligible nodes as primary name servers for the applicable HCP secondary zone or stub zone. You register a node by listing its IP addresses in the secondary zone or stub zone definition.

For any given HCP domain, all storage nodes with IP addresses defined for the applicable network can act as name servers for the HCP DNS manager, regardless of whether they’re registered as primary name servers. However, for HCP to be accessible over that network, at least one registered node must be running. Therefore, you need to register a sufficient number of nodes for each network to minimize the risk that all registered nodes for a given network will fail at the same time.

Tip: If HCP has a small number of storage nodes, consider registering them all as primary name servers. The more nodes you register, the more distributed the DNS queries will be.

When defining a secondary zone or stub zone for an HCP domain, you specify a fully qualified domain name for the HCP system. This is the name of the domain associated with the network that is defined in HCP.