When using a management VPRN, to allow DNS resolution via VPRN, as an example, DNS for all packets - routed through the Global Routing Table or the VPRN - the user must enable a redirect-vprn configuration under the base DNS server. The configuration is enabled using the configure router dns redirect-vprn service service-id command. When the redirect-vprn configuration is enabled, all packets have their URLs resolved through the configured redirect-vprn service. Only a single redirect-vprn configuration is supported.
As a prerequisite for the DNS resolution through the VPRN, the VPRN DNS server must be configured with at least a primary-dns IP address (IPv4 or IPv6). If the VPRN DNS server is not configured, all packet resolution fails, even if the BOF DNS server is configured, because the redirect-vprn configuration forces all packets through the redirect-vprn service for resolution.
The redirect-vprn command is not available at bootup, because the configuration is not loaded yet. Until the redirect-vprn command is executed, all DNS resolution is possible only through the BOF DNS configuration. The redirect-vprn configuration becomes active at runtime, after the configuration file is loaded and the redirect-vprn command is executed.
If the redirect-vprn command is not configured, DNS resolution occurs as follows:
The global routing packets use the BOF DNS server.
The VPRN packets use the configured VPRN DNS server. If the VPRN DNS server is not configured, the resolution occurs through the BOF DNS server.
For information about management VPRNs, see Node Management Using VPRN in the 7450 ESS, 7750 SR, 7950 XRS, and VSR Layer 3 Services Guide: IES and VPRN.