Hi, when I use logback without a logback.xml, everything works fine, but when I add a logback.xml file, I get an UnknownHostException. This happens in the ch.qos.logback.core.util.ContextUtil class, when InetAddress.getLocalHost() is called. In our environment, there is no hostname mapping available to the JVM, so the JVM cannot find one. So why does logback require the IP at this point? Regards Jan Ehrhardt