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.

When you set up an IBM® Notes® workstation on the TCP/IP network, you normally rely on DNS to resolve the name of the workstation's IBM® 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 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.

Note: 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:

  • The user's home server is down.
  • The user's home server is not running TCP/IP.
  • The user's home server cannot be resolved over TCP/IP.
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 following topics:

  • Ensuring DNS resolves in NRPC Best practices...
  • Policies

The pass-through server

By connecting to a pass-through 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 pass-through server, it may not be possible for the pass-through server to resolve the name of the destination server. In this case, do one of the following:

  • On the Notes® workstation, create a Connection document that includes the IP address of the destination server.
  • On the pass-through server, create a Connection document to the destination server.

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.

  • Place a hosts file, which is a table that pairs each system name with its IP address, on every system that needs private access. Set up each system so that it accesses the hosts file before accessing DNS.
  • Create a Connection document that contains the destination server's IP address on every Notes® workstation and Domino® server that needs to access that server.

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.

  • Direct NetBIOS broadcast -- The system sends out a name broadcast message so that all of the systems on the local network segment can register the name and IP address in their name cache. If you must use NetBIOS over IP and use Domino® with both the NetBIOS and TCP/IP port drivers, avoid name-resolution problems by giving the Domino® server and the system different names.

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 Microsoft Windows systems to access in their name lookups.

  • Windows Internet Name Service (WINS) -- Uses NetBIOS broadcasts. Unlike DNS, which is static in nature, WINS is dynamic. Note that the TCP/IP stacks of Macintosh and UNIX client systems may not be able to access the WINS server.
  • LAN Manager Hosts (LMHosts) -- A static hosts file method.
Note: 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.