Host and device name resolution
In this section you specify how host names and network device names are resolved when Resolve host and device names is enabled in the Data section of the Administration > Administration > User Preferences page.
Search domains
When the NetProfiler appliance looks up the address of a host name that does not include a domain name, it appends a specified domain name to the host name in order construct a fully qualified domain name and perform the search. You can specify multiple search domains as a comma-separated list. The NetProfiler tries to resolve the host name using each domain in the search list in the order in which it appears in the list. For example, assume that you specified a comma-separated list of domain names, such as
newcompany.com,emea.newcomapny.com,oldcompany.com
Also, assume that you specified "finance1" in a report criteria field that accepts host names. The NetProfiler appliance would append the first search domain in the list and use finance1.newcompany.com in a lookup. Then it would append the second domain in the list to the host name and use finance1.emea.newcompany.com in another lookup, and so on. It would attempt to find the address by looking up the host name and a fully qualified domain name based on each domain in the search list.
If a host name is registered in more than one domain, NetProfiler uses the first IP address it obtains. Therefore, it is best to enter the list of search domains with the most preferred domain first.
DNS servers - Specify the addresses of the DNS servers that the NetProfiler accesses to look up the host name associated with an IP address or the IP address associated with a host name. Leaving the primary and secondary DNS server address fields blank disables the use of DNS.
This section enables DNS name resolution in general. Name resolution can be enabled or disabled for hosts and network devices separately in their respective sections.
Edit /etc/hosts - opens an editor for modifying the hosts file. This file includes address-name assignments required by the appliance, which are not editable, and address-name assignments that are user-defined. Assignments that you define in the /etc/hosts/ file take precedence over DNS lookups. They are not affected by configuration changes. DNS name resolution must be enabled for this feature to be available.
Name resolution
If NetProfiler can resolve names on both IPv4 and IPv6 networks, you can specify which takes precedence.
Host name resolution
Enable DNS name resolution for hosts
Enables DNS name resolution for hosts and sets limits to protect your DNS server from excessive traffic loads. You can limit the number of host lookups that the NetProfiler appliance requests at one time. For example, if you specify that NetProfiler is to resolve no more than 1000 hosts at a time, then it will send 1000 DNS lookup requests and wait for all 1000 to be answered or timed out before sending the next thousand.
You can also limit the number of lookups for any one table, graph or list on a report. If the number of hosts in any one table, graph or list exceeds the specified limit, then all hosts beyond the limit are reported by their addresses instead of by their host names. This setting applies to Reports pages and the Host Groups page.
Enable DHCP name resolution for hosts managed by DHCP
Enables name resolution for hosts managed by DHCP. When this option is selected, the NetProfiler appliance looks for the name assignment in its local DHCP data records. This requires DHCP integration to have been configured. more
If both the DNS and DHCP options are selected, then the NetProfiler first looks in its DHCP data records before performing a DNS lookup.
When it finds the name of the host, it displays the host name on user interface pages that list hosts. It also displays the domain to which the host belongs, unless you have selected the Suppress DHCP/DNS search domains option in the Data section of the Administration > User Preferences page.
IPv4 takes precedence over IPv6 or IPv6 takes precedence over IPv4
This setting determines which address takes precedence when one DNS name is assigned to both IPv4 and IPv6 addresses. If the same DNS name is assigned to both an IPv4 address and an IPv6 address, NetProfiler must determine which address to use when resolving the DNS name. It uses the IPv4 address by default. However, you can set it use the IPv6 address instead.
Network device name resolution
Enable SNMP name resolution for devices
Enable the NetProfiler appliance to use SNMP to obtain the names of network devices that are sending traffic information to it. This requires SNMP polling to be configured.
Enable DNS name resolution for devices
Specifies how often the cache containing the DNS names for network devices is refreshed. Additionally, the following conditions cause the cache to be cleared and rebuilt:
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Enabling or disabling DNS name resolution globally in the Host name resolution section.
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Modifying the search domains setting.
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Modifying the primary or secondary DNS server addresses.
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Using the Edit /etc/hosts button to edit the /etc/hosts file.
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Clicking the Clear device DNS cache button.
Precedence
If both SNMP and DNS name resolution for network devices are enabled, you can select which takes precedence over the other.