About 80% of us who graduate from a university with an IT specialty do not end up becoming a programmer. Many get technical support, system administrators, computer setup wizards, digital equipment sales consultants, IT managers and so on.
This article is for those 80% who have just graduated from a university with an IT specialty and have already begun monitoring vacancies, for example, to the position of system administrator or his assistant, or a field engineer to an outsourcing company, or to technical support of the 1st / 2nd line.
And also for self-study or for training new employees.
During my career in the field of IT, I encountered such a problem that universities do not give the most basic base regarding networks. I first encountered this myself, when, after graduating from university, I went for interviews in 2016 and could not answer simple (as it seems to me now) questions. Then, of course, it seemed to me that I had talked about it and did not finish my studies at the university. But as it turned out the case in the educational program. Since now, I also encounter this knowledge gap when I train new employees.
And then, I had to study many articles on the Internet before I understood the basic points, and that now, asking the young specialists topics for study, they can hardly find and learn the necessary. This is due to the fact that the Internet has a huge number of articles and they are all fragmented by topic, or written in too complicated a language. Plus, most of the information at the beginning of their articles contains mostly just scientific definitions, and then immediately complex technologies for use. The result is a lot of that for a beginner is still completely incomprehensible.
That is why I decided to collect the main topics in one article and explain them as simply as possible "on the fingers."
I immediately warn that there will be no in-depth information in the article, only the very base and the most basic.
Topics covered:
- WAN and LAN
- IP-
- NAT
- DHCP-
- (, , , )
- UDP TCP
1.
(WAN) (LAN).
(, , /, ..) , .
. (, Google, VK, Instagram, YouTube AmoCRM) .
, . . ( ) .
, , .
, N . , , .
N . .
, .
2. IP-
IP-. , .
(, , , № , № ).
(, ) . , ip- , , 192.168.X.X
.
:
192.168.X.X
, , ip- ( windows), ipconfig
, ip- 192.168.88.251
, ip- , . ip- .
ip- — ip-, — .
. ip-.
, ( ) ip- 91.132.25.108
ip- 172.17.135.11
ip- 192.168..
ip- 2ip.ru
!
ip-, ip. ip- ( , ) ip-.
ip- , , ip- .
ip- 172.17.132.2 (. ). ip- . . .
, . ip-, ip- ip-, VPN. ip- .
3. NAT
, “ ip-” , ip-, ip.
, ip-, , ip-, NAT (Network Address Translation) — ip-.
NAT .
:
1. : ip- 91.105.8.10 .
ip-. ip-.
, , 1 ip- 192.168.1.3 , , 1 , NAT, ip- 1 ip- 91.105.8.10
, , NAT ip- 192.168.1.3, 1.
2. : , ip- .
1(192.168.1.3) NAT' ip- 172.17.115.3, -, ip- NAT’ ip- 91.105.108.10, ( ).
, , NAT’.
, . , sip- VoIP ip-.
NAT, , , NAT .
4. DHCP —
, , ( ) , ip- .
Wi-Fi, , , , ip- .
ip- ?
DHCP-.
DHCP-. IP-, ip-.
?
, , DHCP- ip-.
, , ip- 192.168.1.10, ip- 192.168.1.35
ip- , . , , .
, DHCP- ip- .
DHCP- . .
, 192.168.0.2-192.168.0.255, 192.168.1.2-192.168.1.255, Wi-Fi 192.168.5.2-192.168.5.255 (. )
, . , , .
.
.
!
web-, , ip- , .
:
1 ip- 10.10.5.2 web- ip- ip- 192.168.1.3, . . ip-, 192.168.1.X, 3 (192.168.1.5).
(172.17.17.12) 4 (172.17.17.10).
, , web- ip-, ip-, , .
5. (, , , )
, , IT ( .) , , , .
, - , .
.
) ,
. , , .
.
. “”.
, , , , RouterOS Mikrotik. .
)
. . ().
() . , , .
. ip- .
4-5 . , , . 24 24 .
, web- .
)
, . .
, .
MAC , . .
, , .
6.
) Ping
ip- , “”.
ping “ip-”.
“” dns google , , ( 83 ).
ip- , :
.
Ping :
-t -”” ( Ctrl+)
- - “” (//)
“-” , “dns.google”.
“-t” ping , , Ctrl+C.
.
, 418 , , 83 418 / ip- .
, .
, dump. .
! ICMP (- , - ), "" , .
“” ip- . , .
ip- :
, ip- 178.248.237.68
)
.
- . .
Windows “tracert” ip- :
, ya.ru
Linux traceroute.
, VoIP .
) whois
ip- .
, ip- 145.255.1.71. whois 145.255.1.71
ip-, , , , ..
Linux. .
, Windows .
7. TCP UDP
TCP UDP.
TCP . . , TCP .
, , , .
TCP . , , , . ..
UDP , TCP. . - , .
UDP?
, TCP . UDP . , ip- .
, WhatsApp Viber UDP. , , Skype WhatsApp Viber.
UDP , .
, , .
- , NAT .
TCP, , , UDP.
UDP , . UDP, , TCP UDP.
.
, , .
I tried to put together 7 of the most important, in my opinion, moments, the knowledge of which will help the young “IT specialist” go through the first stages of an interview for “IT” positions or at least just make it clear to the employer that you clearly know more than an ordinary user.
Study, take notes. I hope that the article will benefit many.