ADNR can manage two types of sysplex resources, including server applications and the traditional DNS mappings of host names to IP addresses. Server applications are represented in ADNR as server groups using the server_groups statement. Traditional DNS host name-to-IP address mappings are represented as host groups using the host_groups statement. For more information about server groups and host groups, see Identifying the sysplex resources to be managed by ADNR.
ADNR can dynamically create application-specific host names in a name server to represent a cluster of equivalent servers in the sysplex. For example, the name ztelnet.mvsplex.mycorp.com can represent all TN3270E Telnet server applications in the sysplex. Any TCP or UDP server application in the sysplex can be managed by ADNR and have application-specific host names dynamically added and removed from a name server to represent active instances of those servers. As server applications become available, ADNR dynamically adds resource records representing those instances to the name servers managed by ADNR. As those server applications or their systems become unavailable, ADNR dynamically deletes resource records representing those instances from the name servers it manages. These types of DNS names can be used to connect to any active instance of a particular type of server. ADNR also dynamically creates and removes application-specific host names that represent individual instances of server applications as they become available and unavailable.
Most IP addresses in the home lists of sysplex hosts can be dynamically added to the name server as traditional DNS name-to-IP address mappings. As IP addresses are removed from a home list (for example, by issuing a VARY TCPIP,,OBEYFILE command), the DNS resource records representing those IP addresses are dynamically removed from the ADNR-managed name servers. These types of DNS names can be used to connect to any resource in the sysplex, or on a particular sysplex host without regard to which servers are available on that system, such as when using the ping or traceroute commands.
The IP addresses that are added to DNS by ADNR can be interface addresses, static VIPAs, or dynamic VIPAs (DVIPAs). A small set of addresses cannot be managed by ADNR because of z/OS® Load Balancing Advisor restrictions. For more information, see Step 7: Configure the external load balancers and the restriction that certain classes of IP addresses must not be coded for members in the load balancer.
You might want to make some sysplex resources visible to some set of clients and not visible to other sets of clients. For example, you might want to add DNS entries to make some sysplex resources visible to intranet clients, but not make the resources visible to Internet clients. There are several ways to accomplish this. Some methods can be accomplished with only name server configuration, others might involve ADNR configuration. For more information, see Split DNS (views).