Demilitarized Zone. The Network-Area, which contains Computers accessable from outside.
The Computers in DMZ can NOT access Computers in local net. The Computers in local net CAN access Computers in DMZ, so that they are forwarded to the internet.

SSH is an application, which encrypts network traffic (packages) and redirects them to the receiver SSH applicaiton.
The receiver SSH decrypts the packages and redirects them to the initial Ports.
So any port may be bypassed thrpugh an ssh tunnel

Checks whether the network can be reached. Resolves the ip by domain.

Checks the domain by ip. Can use a concrete DNS server (e.g. the domain DNS server to resolve the domain controller ip in AWS)

nslookup google.com
Server:         21.1.0.2
Address:        21.1.0.2#53

Non-authoritative answer:
Name:   google.com
Address: 216.58.211.174




nslookup basic.local 21.1.2.35
Server:         21.1.2.35
Address:        21.1.2.35#53

Name:   basic.local
Address: 21.1.3.174
Name:   basic.local
Address: 21.1.2.35

traceroute - print the route packets take to network host

https://www.lifewire.com/traceroute-linux-command-4092586

traceroute google.com
traceroute to google.com (216.58.211.174), 30 hops max, 60 byte packets
 1  ec2-79-125-0-176.eu-west-1.compute.amazonaws.com (79.125.0.176)  12.416 ms e                                                                   c2-79-125-0-178.eu-west-1.compute.amazonaws.com (79.125.0.178)  18.128 ms ec2-79                                                                   -125-0-182.eu-west-1.compute.amazonaws.com (79.125.0.182)  21.017 ms
 2  100.66.8.118 (100.66.8.118)  13.014 ms 100.66.8.106 (100.66.8.106)  16.647 m                                                                   s 100.66.8.112 (100.66.8.112)  19.972 ms
 3  100.66.10.204 (100.66.10.204)  19.664 ms 100.66.10.6 (100.66.10.6)  14.013 m                                                                   s 100.66.11.106 (100.66.11.106)  16.720 ms
 4  100.66.6.3 (100.66.6.3)  22.333 ms 100.66.7.139 (100.66.7.139)  14.137 ms 10                                                                   0.66.7.169 (100.66.7.169)  20.096 ms
 5  100.66.4.125 (100.66.4.125)  16.902 ms 100.66.4.99 (100.66.4.99)  16.893 ms                                                                    100.66.4.201 (100.66.4.201)  20.315 ms
 6  100.65.11.161 (100.65.11.161)  0.708 ms 100.65.9.1 (100.65.9.1)  3.319 ms 10                                                                   0.65.10.33 (100.65.10.33)  1.580 ms
 7  176.32.106.204 (176.32.106.204)  1.021 ms  1.016 ms  1.009 ms
 8  * * *
 9  52.93.7.156 (52.93.7.156)  13.002 ms * *
10  52.93.7.37 (52.93.7.37)  1.274 ms 52.93.7.150 (52.93.7.150)  2.957 ms 52.93.7.144 (52.93.7.144)  45.110 ms
11  72.14.204.244 (72.14.204.244)  1.107 ms  1.083 ms 52.93.7.45 (52.93.7.45)  1.216 ms
12  209.85.252.196 (209.85.252.196)  1.254 ms 72.14.204.244 (72.14.204.244)  1.193 ms 209.85.252.196 (209.85.252.196)  1.264 ms
13  209.85.241.139 (209.85.241.139)  1.307 ms 209.85.252.196 (209.85.252.196)  1.039 ms 209.85.241.139 (209.85.241.139)  1.046 ms
14  209.85.241.139 (209.85.241.139)  1.014 ms dub08s01-in-f14.1e100.net (216.58.211.174)  0.942 ms 209.85.241.139 (209.85.241.139)  1.014 ms