Which type of domain name system server performs a full name resolution request?

To ensure network reliability and service access security, do not expose the IP addresses of the nodes that provide services. Instead, use domain names to provide object services.

Basic Knowledge of Domain Name Resolution

• What Is DNS resolution?

  When you need to access a service on the Internet, an IP address is used. However, the IP address is difficult to remember. Therefore, a domain name is used instead of an IP address. A domain name is an address translation system created for the ease to remember. Domain name resolution is a process of translating a domain name into an IP address. Domain name resolution requires a Domain Name System (DNS) server.

• What are the types of domain name resolution records?

  Domain name resolution records are stored in DNS zone files. The following describes two types of DNS records involved in configuring a DNS server in the object service:

  • A record: host record, which is used to specify the mapping between a host name (or domain name) and the IP address of the host.
  • Name Server (NS) record: DNS server record, which is used to specify the DNS server where the domain name is resolved.
  • CNAME record: alias record, which is used to map a domain name to another domain name. When the DNS server encounters a CNAME record, it re-performs a query based on the mapped target.
• What are the DNS query modes?
  • Recursive: In this mode, after receiving a request from a client, the DNS server must return an accurate query result to the client. If the DNS server does not find the queried information locally, it queries other servers and sends the query result to the client.
  • Iterative: The DNS server provides other DNS server addresses that can be used to parse query requests. When a client sends a query request, the DNS server does not directly return the query result but notifies the client of another DNS server address. The client submits a request to the DNS server and repeats until the query result is returned.

Which Domain Names Need to Be Planned for the Object Service?

To ensure the availability of basic services, you need to plan the following domain names for the object service: global domain name, region domain name, cluster domain name, location service (LS) domain name, and POE domain name. Only the global domain name is used externally. Other domain names are used internally. In a single-cluster scenario, the object service does not need to connect to an external DNS server. In this case, the global domain name, region domain name, and cluster domain name are the same.

Table 1-1 describes the services provided by each domain name and the IP address used to resolve each domain name.

Table 1-1 Domain name of the object service

Generally, the global domain name is the entry for accessing the object service. However, there are special scenarios: In the single-cluster scenario, if a user creates a service network of the object service by creating subnets and access zones, and multiple subnets are configured, but the object service client does not connect to all subnet networks, the user needs to use the full domain name of the partition in each subnet to access the object service.

In the single-cluster scenario, when the object service client is connected to all subnets, the global domain name of the object service can be used to access the object service.

In the multi-cluster scenario, if the service network is configured with multiple subnets, the object service client must be connected to all subnets and the global domain name of the object service is used to access the object service.

How Does the Object Service Resolve Domain Names?

The object service provides the internal DNS module, which interconnects with the external DNS to provide the domain name resolution service. Figure 1-1 shows the logical relationship of DNS.

The following describes the interaction between the internal DNS and external DNS services. The POE domain name is used for account authentication, and the location service domain name is used for bucket metadata query. Parsing of the POE domain name and location service domain name is not described in this document.

Figure 1-1 Logical relationship of DNS

• External DNS

  The DNS server is provided by the customer or deployed on the public network. It is used to resolve external public network access requests and forward the requests to the internal DNS of the object service. The external DNS server provides the following functions:

  • Global domain name resolution

    Global domain names are resolved to a global DNS IP addresses.

  • Regional domain name resolution

    Region domain names are resolved to region DNS IP addresses.

  • Cluster domain name resolution

    Cluster domain names are resolved to cluster DNS IP addresses.

• Internal DNS

  Includes global DNS, region DNS, and cluster DNS, which are implemented by the object service. The global DNS and region DNS in the default region provide the global DNS function. The region DNS in a non-default region provides the DNS function in the local region, and the cluster DNS provides the DNS function for the local cluster.

  • Global DNS

    This function is provided only in clusters of the default region and resolves global domain names into the corresponding region domain names.

  • Region DNS

    This function is provided only in clusters of the default region and resolves global domain names into the corresponding region domain names.

  • Cluster DNS

    This function is provided by each cluster. The domain name of a cluster is resolved to the IP address of the node that provides the object service in the cluster.

Domain Name Resolution Process

This section uses an example to describe the domain name resolution process. Table 1-2 describes the domain name planning. The following domain names must be recorded on the external DNS server.

Table 1-2 Domain name planning

Figure 1-2 uses the bucket1.obs.myobsdomain.com request as an example to describe domain name resolution.

Figure 1-2 Domain name resolution process

1. The client sends a domain name (bucket1.obs.company.com) resolution request to the local DNS.
2. The local DNS cannot resolve this domain name and forwards the request to the external DNS. The external DNS cannot resolve the domain name but knows that obs.company.com can be queried in the global DNS. Therefore, the external DNS returns the DNS IP address of obs.company.com to the local DNS.
3. The local DNS sends a domain name (bucket1.obs.company.com) resolution request to the global DNS and obtains the alias of bucket1.obs.company.com (bucket1.obs.region1.company.com) from the global DNS.
4. The local DNS sends a domain name (bucket1.region1.company.com) resolution request to the external DNS and obtains the DNS IP address of bucket1.region1.company.com from the external DNS, that is, the region DNS.
5. The local DNS sends a domain name (bucket1.region1.company.com) resolution request to the region DNS to obtain the alias (cluster1.company.com) of bucket1.region1.company.com.
6. The local DNS sends a domain name (cluster1.company.com) resolution request to the external DNS and obtains the DNS IP address of cluster1.company.com from the external DNS, that is, cluster DNS.
7. The local DNS sends a domain name (cluster1.company.com) resolution request to the cluster DNS and obtains the IP address of the node that provides the bucket1 object service from the cluster DNS.

Configuring the DNS service

Configuring the DNS service includes configuring an external DNS server, interconnecting with the external DNS, and configuring domain name resolution on the client. For details, see the OceanStor 100D 8.0.3 Basic Object Service Configuration Guide and OceanStor Pacific Series 8.1.0 Basic Service Configuration Guide for Object.

Note the following when configuring an external DNS server:

• The DNS query mode must be set to recursive.
• In the special scenario described in Which Domain Names Need to Be Planned for the Object Service?, set the prefix of the global domain name to the prefix of the partition global domain name.
• In versions earlier than OceanStor Pacific series 8.1.0, the address that provides the domain name service is the service IP address of any two nodes in the cluster. In OceanStor Pacific series 8.1.0, the address that provides the domain name service is the DNS service IP address of the object in the subnet. Therefore, when you configure the external DNS server, the configuration of the A record varies with the version.

Which type of DNS performs a full name resolution request?

What are the 3 types of DNS?

How does DNS resolve a domain name?

What is the importance of using DNS name resolution?