MID Server capabilities

  • Release version: Yokohama
  • Updated January 30, 2025
  • 3 minutes to read
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    Summary of MID Server capabilities

    MID Server capabilities specify the functions a MID Server can perform within an IP address range, enabling ServiceNow applications to select the most suitable MID Server. These capabilities control how MID Servers discover and interact with devices and services, providing precise targeting and efficient workload distribution.

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    Key Features

    • Nmap Capability: Assigned automatically when the Network Mapper (Nmap) scanner is installed on a MID Server for credential-less discovery. It cannot be manually added or removed.
    • Capability Values: Capabilities can have blank, single, or wildcard () values. A blank value means the MID Server can locate any device using that capability’s protocol. A defined value restricts the MID Server to devices matching that exact value, except for the Resolve DNS capability, which allows partial string matches.
    • Capability Name and Value Combinations: Starting with the Madrid release, capabilities appear with their values in selection lists, helping users distinguish between capabilities with different values—essential for targeting specific logical datacenters or environments.
    • MID Server Selection Algorithm: The system selects a MID Server based on server status, applications, IP range, and capabilities in sequence. It prioritizes exact value matches first, followed by wildcard matches, and finally the special capability name ALL, which matches all requests ignoring value constraints.
    • Scripted Capability Value Matching: Custom scripts can be used to control capability matching beyond exact string matches. For example, the Resolve DNS capability uses a script to match device names ending with a specified domain, allowing flexible DNS resolution based on domain suffixes.

    Practical Application for ServiceNow Customers

    By configuring MID Server capabilities and their values appropriately, customers can ensure that ServiceNow applications such as Orchestration select the most suitable MID Server for device discovery and management tasks. This enables precise control over which MID Server handles specific protocols, IP ranges, or logical environments, improving discovery accuracy and operational efficiency.

    Capabilities like Resolve DNS enhance device identification by allowing domain-based device matching rather than exact names, which is useful in complex network environments. The automatic management of capabilities like Nmap reduces administrative overhead while maintaining secure discovery practices.

    MID Server capabilities define the specific functions of a MID Server within an IP address range.

    Nmap capability

    The Nmap capability is only assigned to MID Servers for which the Network Mapper (Nmap) scanner has been installed for credential-less Discovery. This capability cannot be added to or removed from any MID Server manually. For instructions on installing or uninstalling Nmap, see Install and uninstall Nmap on a MID Server

    MID Server capability values

    Capabilities provided in the base system do not have a defined value string. The capability value can be blank, a single value, or a * (wildcard). A MID Server configured to use a capability that has no value can locate any device using that capability's protocol. If a capability has a defined value, the MID Server using that capability finds only those devices using that protocol that match the value string exactly. The exception to this is the Resolve DNS capability, which is configured to resolve any DNS name into an IP address using a partial string match. The * (wildcard) will match a request capability specifying any non-blank value.

    Starting with the Madrid release, the [capability name]:[value] combination appears in the slushbucket when you add a capability to a MID Server. This combination allows you to see all the capabilities that have different values, even if the capability name is the same. For example, if you are using the Cloud Management capability, and you use the value field to specify the us-west logical datacenter on one of the capability records, you can see the combination in the Collection list.

    Capability name and value combination

    MID Server selection

    The MID Server is selected using an algorithm based on the capabilities available. The selector produces a list of suitable MIDs using filters in the following order: server status > applications > IP range > capabilities. The algorithm searches the capabilities in the following sequence and, if a step finds at least one MID server, the remaining steps are skipped:
    1. Exact value match: Find each MID Server containing capabilities with name/value pairs with an exact match to all requested capability name/value pairs. Blank is a valid value. * (wildcard) values are ignored.
    2. Wildcard value match: The same as an exact value match, but also allows a non-blank request value to match MID server capability records containing value *.
    3. Special capability name ALL: Find each MID Server containing the special capability name ALL, ignoring capability's value field.
    Note:
    If the requested capability name does not exist in the ecc_agent_capability table, BadArgumentException is thrown rather than falling back to the ALL capability.

    Scripted MID Server capability value matching

    You can use value tests to create capabilities that find devices using values without requiring exact string matching. Action on these values is controlled by a user-defined script.

    The Resolve DNS capability is provided in the base system and is configured to resolve DNS names into IP addresses for devices whose names end with a specified domain name. The capability Value entered is automatically prefaced with a dot during processing to match domain syntax. This value can contain one or more sub-domains, but must include the end of the domain string. Matching devices must end with the identical syntax. The script for the Resolve DNS capability determines if a device name matches the criteria defined by Value. If a match exists, the platform performs the address resolution automatically. For example, if the value for the Resolve DNS capability is service-now.com, the MID Server with this capability finds lnxlab01.sandiego.service-now.com and dbsrv101.sanjose.service-now.com. If the value is changed to sandiego.service-now.com, then the MID Server finds only lnxlab01.

    Note:
    If Value in the Resolve DNS capability is blank, then all domains match.

    To view the script for evaluating this capability, navigate to MID Server > Capability Value Tests and select Resolve DNS from the list.

    MID capabilities