NRPC name-to-address resolution over TCP/IP
In the TCP/IP protocol, the method most commonly used to resolve server names to network addresses is the Domain Name System (DNS), an Internet directory service developed both to allow local administrators to create and manage the records that resolve server names to IP addresses and to make those records available globally. While the POP3, IMAP, LDAP, and HTTP services use DNS directly, the NRPC service uses a combination of the Notes Name Service and DNS to resolve server names to network addresses.

For background information on how the Notes Name Service works with name-resolver services such as DNS, see the topic Resolving server names to network addresses in NRPC.

Within DNS, "domain" refers to a name space at a given level of the hierarchy. For example, the .com or .org in a Web URL represents a top-level domain. In a domain such as, a DNS server -- that is, a server running DNS software -- in the Acme company stores the records for all Acme servers, and an administrator at Acme maintains those records.

When you set up an IBM Lotus Notes workstation on the TCP/IP network, you normally rely on DNS to resolve the name of the workstation's IBM Lotus Domino home server the first time the workstation tries to connect to it. As long as the Notes workstation and Domino home server are in the same DNS domain level, DNS can accomplish the resolve.

When to edit the Net Address field in the Server document

The default format for a server's TCP/IP network address in Lotus Domino is its fully qualified domain name (FQDN) -- for example, -- based on the DNS record and the IP address references in the system's TCP/IP stack. When a Notes workstation or Domino server requests this name, the TCP/IP resolver passes it to DNS, and DNS resolves the name directly to the IP address of the destination server, regardless of the DNS domain level of the requesting system.

If you do not want to enter the FQDN in the Net Address field, you can change it to the simple IP host name -- for example, app01 -- either during server setup or later by editing the Server document. For example, you might use the simple IP host name if you are setting up multiple TCP ports for NRPC, a configuration in which using the FQDN for each network address can cause connection failures if the Notes Name Service returns the FQDN for the wrong TCP port. In this case, using the simple IP host name ensures that DNS does a lookup in all domain levels within the scope of the domains defined in the requesting system's TCP/IP stack settings.

Caution In a production environment, do not use IP addresses in Net Address fields. Doing so can result in serious administrative complications if IP addresses change or if Network Address Translation (NAT) connections are used, as the values returned by the Notes Name Service will not be correct.

Secondary name servers
To ensure that the Notes Name Service is always available over TCP/IP, when you set up a Notes user, you can designate a Domino secondary name server that stands in for the home server in these situations:

Note In companies using multiple DNS domains, a Domino secondary name server ensures that a Notes workstation can connect with its home server even when the home server is in a different DNS domain. You can use policies to automate the setup of secondary name servers.

For more information, see the topics Ensuring DNS resolves in NRPC -- Best practices and Policies.

Special case: The passthru server
By connecting to a passthru server, Notes users can access servers that do not share a network protocol with their systems. If both the Notes workstation and destination server are in a different Domino domain from the passthru server, it may not be possible for the passthru server to resolve the name of the destination server. In this case, do one of the following:

For more information on setting up Notes users to access a passthru server, see the topic Passthru servers and hunt groups.

Internal alternatives to DNS
If you don't use DNS at your site or if a Domino server is not registered with DNS (as is sometimes the case if the server offers Internet services), use one of these methods to enable each Notes workstation and Domino server to perform name resolution locally. Keep in mind that the upkeep required for both of these approaches is considerable.

Alternative IP name services
Microsoft networking services offers four additional methods of IP address resolution. These methods are not as reliable as traditional DNS and hosts files and can cause name and address confusion. For best results, do not use these methods when also using the Notes network port for TCP/IP.
Master Browser cache (for NT domains or SAMBA servers) -- Collects broadcasted names and IP addresses and publishes them across the NT domain to other Master Browser systems for Windows systems to access in their name lookups.
Caution On a Windows system, the combination of the system's native NetBIOS over IP name-resolver service and DNS can cause name resolution failure for the Domino server name.

For information on avoiding this problem, see the topic Server name-to-address resolution over NetBIOS.

See also