MID Server capabilities
Summarize
Summary of MID Server capabilities
MID Server capabilities define the specific functions and protocols a MID Server can perform within an IP address range. These capabilities enable ServiceNow applications to select the most appropriate MID Server for tasks such as Discovery and Orchestration by matching the MID Server’s capabilities with the required functions.
Show less
Key Features
- Nmap Capability: Assigned only to MID Servers with the Network Mapper (Nmap) scanner installed for credential-less Discovery. This capability cannot be manually added or removed.
- Capability Values: Capabilities may have no value, a specific value, or a wildcard (). A blank value allows the MID Server to find any device using the protocol, while a defined value restricts matching to devices with that exact value. The Resolve DNS capability uses partial string matching for domain names.
- Capability Selection Algorithm: MID Servers are selected based on server status, applications, IP range, and capabilities. The search for a suitable MID Server follows an order: exact value matches first, then wildcard value matches, and finally the special ALL capability name. If a requested capability name does not exist, an error is thrown instead of defaulting to ALL.
- Scripted Capability Value Matching: Allows for flexible value tests beyond exact string matches, controlled by user-defined scripts. For example, the Resolve DNS capability uses a script to match device names ending with specific domain names, enabling automatic IP resolution.
- Capability Configuration: Since the Madrid release, capability name and value pairs appear together in selection lists, helping administrators distinguish between capabilities with the same name but different values (e.g., logical datacenter locations).
Practical Application for ServiceNow Customers
By configuring MID Server capabilities accurately, you ensure that ServiceNow applications such as Discovery and Orchestration can efficiently select the most suitable MID Server for specific network environments and protocols. Understanding how capability values and matching algorithms work helps optimize MID Server usage and prevents selection errors. Additionally, leveraging scripted capabilities like Resolve DNS enhances dynamic device identification and IP resolution in complex domain environments.
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.
MID Server selection
- 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.
- 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 *.
- Special capability name ALL: Find each MID Server containing the special capability name ALL, ignoring capability's value field.
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.
To view the script for evaluating this capability, navigate to and select Resolve DNS from the list.