Information
The loss of connectivity to a particular authoritative time source will result in the loss of time synchronization (free-run mode) and increasingly inaccurate time stamps on audit events and other functions.
Multiple time sources provide redundancy by including a secondary source. Time synchronization is usually a hierarchy; clients synchronize time to a local source while that source synchronizes its time to a more accurate source. The network device must utilize an authoritative time server and/or be configured to use redundant authoritative time sources. This requirement is related to the comparison done in CCI-001891.
DOD-approved solutions consist of a combination of a primary and secondary time source using a combination or multiple instances of the following: a time server designated for the appropriate DOD network (NIPRNet/SIPRNet); United States Naval Observatory (USNO) time servers; and/or the Global Positioning System (GPS). The secondary time source must be located in a different geographic region than the primary time source.
Solution
Configure the Cisco ASA to synchronize its clock with redundant authoritative time sources as shown in the example below.
ASA(config)# ntp server 10.1.48.8 prefer
ASA(config)# ntp server 10.1.22.2
ASA(config)# end
Item Details
Category: AUDIT AND ACCOUNTABILITY
References: 800-53|AU-8(2), 800-53|AU-8b., CAT|II, CCI|CCI-001890, CCI|CCI-001893, CCI|CCI-004922, CCI|CCI-004923, CCI|CCI-004928, Rule-ID|SV-239924r1015262_rule, STIG-ID|CASA-ND-000940, Vuln-ID|V-239924
Control ID: 52edc0535a751b566a73cdc3182094a12633ff8734300c1bf1344c16b79dacf8