FTP and DNS

   What are the modes of FTP? 

A)  File Transfer Protocol, we use ftp in the process of transferring file from one device to the other.

On any system we can simply install FTP server software and it starts working like a FTP server. In terms of networking we use it for downloading or uploading the ios images from the routers mostly ( Not a very prominent use of ftp ).  Very effective between the transfer of files between the Server and Client. 

   There are two types of FTP.

Passive FTP: - In passive mode, the client establishes both channels (Data and control). In that case, the server tells the client which port should be used for the data channel.

Active FTP: - In active mode, the client establishes the control channel but the server establishes the data channel.

   What are the ports of DNS?


  Domain Name Server.

  DNS server is normally user to convert the IP-ADDRESS into NAME, and vice versa. 
 
    DNS use Port TCP & UDP 53.

  UDP/53 is used when a host or a router wants to resolve a domain name to an IP address (or vice versa).

  TCP/53 is used between two DNS servers when they want to sync or share their databases. Or If the size of the response message is more than 512 bytes, a TCP connection is used.

An example of DNS Lookups