download

The following is a sample resolv.conf file that contains several DNS servers:# cat /etc/resolv.confsearch example.netnameserver 192.168.21.3nameserver 192.168.21.4nameserver 172.18.9.21Chapter 7The first line of resolv.conf in the above example indicates the search domainusing the "search" keyword. Basically, this indicates the local domain name ofour host. When looking up a host name which is not found, this domain name isappended to the hostname and turns it into a Fully Qualified Domain Name (FQDN)and tries looking up the FQDN.The next three lines indicate the three different name servers. System queries eachname server in the order they are listed in resolv.conf. A maximum of threenameserver lines can be defined in this file.If resolv.conf is not present, or no nameserver field is set inresolv.conf, the system will automatically look for a nameserverrunning on localhost.Network Testing ToolsFreeBSD has a number of important network test and troubleshooting tools inthe base system. Hence, you have most of the necessary tools that you need totroubleshoot network connectivity issues. These tools can perform very simpleconnectivity tests as well as very complicated traffic capture and analysis, to help theadministrator spot the potential network issues in the minimum timeframe.PingPing is the most widely used tool to test network connectivity that can be found inalmost every operating system that contains a TCP/IP network stack. While lookingsimple, the ping(8) command is actually a very advanced network test tool that canbe used to solve complex network problems.The simplest usage of the ping command is to transmit ICMP echo-request packetsto a host and show connectivity status to the host, based on the received ICMP echoreplypackets from the host:# ping -c3 192.168.0.20PING 192.168.0.20 (192.168.0.20): 56 data bytes64 bytes from 192.168.0.20: icmp_seq=0 ttl=64 time=0.794 ms[ 121 ]