INTERNET ERROR CODES...!!!
Error 400 - Bad request.
Error 401 - unauthorized request.
Error 403 - forbidden.
Error 404 - Not found.
Error 500 -Internal error.
Error 501 - Not Implemented
Error 502 - Bad Gateway
Error 503 -Service unavailable.
Error 504 - Gateway Time-Out
Error 505 - HTTP Version not
supported/ DNS Lookup Fail/unknown
host
Error 500-599 - Server Errors.....

In real world, these can be used as an answer to your boss or to your friend? :D

Escalator Mechanism

Ping and traceroute examples

C:\> ping -n 1 –r 9 192.168.254.254
C:\> ping –t 192.168.254.254
C:\>tracert -w 5 -h 4 192.168.254.254

Router ping output

"U" = Destination Unreachable
"." = The Network server/service timed out while waiting for a reply
"H" = Host unreachable
"P" = Protocol "
"N" = Network "
"!" = Receipt of a reply
"Q" = Source quench
"M" = Could not fragment
"?" = Unknown packet type

telnet

router/switch with default configuration (fresh from the box) can't be telneted because no password is set.

Cisco IOS access point

Komponen/obyek konfigurasi dari access point Cisco antara lain:

Radio setting,  Multiple SSID, Spanning-tree protocol (Spanning-tree? Akses poin punya spanning-tree?), Local authenticator, Cipher suites and WEP, Tipe-tipe autentikasi, WDS, Fast secure Roaming, Radio management, WIDS (Wireless Intrussion Detection services), RADIUS and TACACS+ server, VLAN, QoS, Filters, CDP, SNMP,

Ping and traceroute/tracert

Whats the difference between ping and traceroute?
Ping is simpler version of traceroute (I can say it so)

Traceroute can also be used to measure the network latency, in addition to network connectivity verification.

Ping and traceroute both can be used to verify the network connection (means: connect or not connect) of a PC or network device(switch, router, accesspoint, etc.)


Ping
Example:
ping 192.168.1.1 (ping with ip address)
ping www.facebook.com (ping with qualified name to test domain name service (DNS) functionality)

Type of ping output (basic):
- Request timed out

- Reply 

 - destination host unreachable: the router has the routes for that network on its routing table but and able to send the ICMP packet but the intended PC receiver don't reply

- destination network unreachable: the router dont have routes for that network on its routing table and don't have gateway of last resort on its routing table.


ICMP TTL
Linux: default 64
Windows 7: default 255

A ICMP that cross two router will draw -2 for the TTL.

Ping result can't tell whether the problem is at the destionation host or a device in the path! The traceroute kicks in!

Traceroute

Upon the traceroute result can you fill this table?

Maximum number of hops
First router IP address
Second router IP address
Destination reached?