Задачка. Найти причину почему не работают некоторые сайты в локалке

iskatel@gate:~$ ping -c 5 support.microsoft.com
PING support.microsoft.akadns.net (157.56.121.21) 56(84) bytes of data.

--- support.microsoft.akadns.net ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 3999ms

iskatel@gate:~$ ping -c 5 amazon.com
PING amazon.com (176.32.98.166) 56(84) bytes of data.

--- amazon.com ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 3999ms

iskatel@gate:~$ ping -c 5 openvpn.net
PING openvpn.net (54.215.128.159) 56(84) bytes of data.

--- openvpn.net ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 4031ms

iskatel@gate:~$ sudo nmap -sS support.microsoft.com

Starting Nmap 6.00 ( http://nmap.org ) at 2013-10-02 14:25 MSK
Nmap scan report for support.microsoft.com (157.56.121.21)
Host is up (0.075s latency).
Not shown: 998 filtered ports
PORT    STATE SERVICE
80/tcp  open  http
443/tcp open  https

Nmap done: 1 IP address (1 host up) scanned in 6.76 seconds
iskatel@gate:~$ sudo nmap -sS amazon.com

Starting Nmap 6.00 ( http://nmap.org ) at 2013-10-02 14:25 MSK
Nmap scan report for amazon.com (72.21.215.232)
Host is up (0.14s latency).
Other addresses for amazon.com (not scanned): 176.32.98.166 205.251.242.54 72.21.194.212
Not shown: 998 filtered ports
PORT    STATE SERVICE
80/tcp  open  http
443/tcp open  https

Nmap done: 1 IP address (1 host up) scanned in 10.07 seconds
iskatel@gate:~$ sudo nmap -sS openvpn.net

Starting Nmap 6.00 ( http://nmap.org ) at 2013-10-02 14:23 MSK
Nmap scan report for openvpn.net (54.215.128.159)
Host is up (0.21s latency).
rDNS record for 54.215.128.159: ec2-54-215-128-159.us-west-1.compute.amazonaws.com
Not shown: 983 filtered ports
PORT     STATE  SERVICE
20/tcp   closed ftp-data
21/tcp   closed ftp
22/tcp   open   ssh
25/tcp   closed smtp
53/tcp   closed domain
80/tcp   open   http
110/tcp  closed pop3
143/tcp  closed imap
161/tcp  closed snmp
443/tcp  open   https
465/tcp  closed smtps
587/tcp  closed submission
993/tcp  closed imaps
995/tcp  closed pop3s
3306/tcp open   mysql
3389/tcp closed ms-wbt-server
9102/tcp open   jetdirect

Nmap done: 1 IP address (1 host up) scanned in 9.45 seconds