Network Troubleshotting

Nslookup

The nslookup utility can be used to lookup the specific IP address(es) associated with a domain name. If this utility is unable to resolve this information, there is a DNS issue.

[root@linuxDev-wms10235 Prog_test]# nslookup www.google.com
Server:  8.8.8.8
Address: 8.8.8.8#53

Non-authoritative answer:
Name: www.google.com
Address: 216.58.196.164

traceroute

Traceroute utility can used to determine more specific information about the path to the destination host including the route the packet takes and the response time of these intermediate hosts.

traceroute to www.google.com (74.125.68.104), 30 hops max, 60 byte packets

 1  gateway (10.0.2.2)  1.008 ms  0.719 ms  0.540 ms

 2  * * *
 3  * * *

 4  * * *

Netstat

when verifying the status of a listening port on a host or to check and see what remote hosts are connected to a local host on a specific port.

Routing Table

[root@linuxDev-wms10235 Prog_test]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0             10.0.2.2        0.0.0.0                UG    100    0        0    enp0s3
10.0.2.0            0.0.0.0         255.255.255.0    U     100    0        0 enp0s3
[root@linuxDev-wms10235 Prog_test]#