Navigation server and navigation system

A navigation system comprising:

• a navigation server that is configured to support a guidance of a user by a navigation client based on communication with the navigation client;
• and
• the navigation client,
• wherein the navigation server includes a first server arithmetic processing element and a second server arithmetic processing element that are configured of a programmable computer,
• the first server arithmetic processing element is configured to search for a route connecting a present location of the user and a destination point,
• the second server arithmetic processing element is configured to determine whether or not a first index value indicating a degree of influence of a predetermined primary event on a passage of the user along a searched route is greater than a first threshold value,
• in a case the second server arithmetic processing element determines that the first index value of a previous searched route is greater than the first threshold value, the first server arithmetic processing element re-searches a route such that the first index value is reduced, and
• in a case it is determined that the first index value of a latest searched route is equal to or less than the first threshold value, the second server arithmetic processing element transmits the latest searched route and confirmation information indicating that the first index value is equal to or less than the first threshold value to the navigation client based on the communication with the navigation client.