Port connection

22 for ssh
80 for http

The port range that a normal (non-root) user can listen on is 1024 through 65535.

Hosts:a machine on the internet that might host services

vagrant@vagrant-ubuntu-trusty-64:~$ ping -c 1 google.com
PING google.com (172.217.24.142) 56(84) bytes of data.
64 bytes from nrt20s01-in-f14.1e100.net (172.217.24.142): icmp_seq=1 ttl=50 time=87.3 ms

vagrant@vagrant-ubuntu-trusty-64:~$ host google.com
google.com has address 172.217.25.238
google.com has IPv6 address 2404:6800:4004:817::200e
google.com mail is handled by 10 aspmx.l.google.com.
google.com mail is handled by 30 alt2.aspmx.l.google.com.
google.com mail is handled by 50 alt4.aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
google.com mail is handled by 20 alt1.aspmx.l.google.com.
vagrant@vagrant-ubuntu-trusty-64:~$ host -t a google.com
google.com has address 172.217.25.238

vagrant@vagrant-ubuntu-trusty-64:~$ dig www.udacity.com

; <<>> DiG 9.9.5-3ubuntu0.10-Ubuntu <<>> www.udacity.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 42131
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.udacity.com.               IN      A

;; ANSWER SECTION:
www.udacity.com.        3081    IN      CNAME   apollo-mesos-elb-berlioz2-prod-885022263.us-west-2.elb.amazonaws.com.
apollo-mesos-elb-berlioz2-prod-885022263.us-west-2.elb.amazonaws.com. 33 IN A 54.186.129.122
apollo-mesos-elb-berlioz2-prod-885022263.us-west-2.elb.amazonaws.com. 33 IN A 52.26.227.216
apollo-mesos-elb-berlioz2-prod-885022263.us-west-2.elb.amazonaws.com. 33 IN A 35.163.216.178

;; Query time: 86 msec
;; SERVER: 10.0.2.3#53(10.0.2.3)
;; WHEN: Sat Dec 10 14:32:18 UTC 2016
;; MSG SIZE  rcvd: 160

CNAMEレコード 【 Canonical NAME record 】 CNAMEレコードとは、DNSで定義されるそのドメインについての情報の種類の一つで、あるドメイン名やホスト名の別名を定義するもの。
ドメイン名に対応するIPv6形式のIPアドレスが書いてある行が「AAAAレコード」
NSレコードは、ゾーン情報を管理するネームサーバー（DNSサーバー）名を定義するレコード

network address

vagrant@vagrant-ubuntu-trusty-64:~$ ip addr show
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN group default
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0:  mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 08:00:27:6c:cb:39 brd ff:ff:ff:ff:ff:ff
    inet 10.0.2.15/24 brd 10.0.2.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fe6c:cb39/64 scope link
       valid_lft forever preferred_lft forever

my ip address
http://test-ipv6.com/