When using pam_ldap and/or nss_ldap and the LDAP server becomes unavailable, why am I unable to log in at the console, even as a local user like root?

It is unfortunately impossible to give a blanket solution to this problem since there is a wide range of ways to set up Pluggable Authentication Modules (PAM) and Name Service Switch (NSS) for Lightweight Directory Access Protocol (LDAP) usage. This article will cover the main issues that people run across as well as some general guidelines.

Timeouts with nss_ldap:

One issue is...