An enterprise uses Huawei routers to deploy an IS-IS network for network-wide communication.

Comprehensive and Detailed in-depth Step-by-Step Explanation:

In IS-IS, the interface cost is a metric used to determine the best path to a destination. Lower-cost paths are preferred over higher-cost paths. By default, IS-IS interface costs can range from 1 to 63 .

Default Cost Range:

IS-IS allows the configuration of interface costs within the range of 1–63 by default. This range is sufficient for most networks.

Maximum Configurable Cost:

The maximum value that can be configured by default is 63 . If there is a requirement for a higher cost range, the metric-style can be changed to wide , which allows the cost range to extend beyond 63.

Option A (67): Incorrect. 67 is not the maximum default value.

Option B (63): Correct. This is the maximum default cost value.

Option C (64): Incorrect. This is beyond the default range.

Option D (68): Incorrect. This is beyond the default range.