How firefox is working & know the DNS ?
- How
firefox know the DNS ?
- /etc/resolv.conf file is used to inform to firefox about the DNS server ip address.
- This file contain the list of DNS IP address, using this IP address firefox send the DNS request to get the IP for given web page(Eg: google.com)
- resolv.conf is the name of a computer file used in various operating systems to configure the system's Domain Name System (DNS) resolver.
- While user give "google.com" and enter, first it will check the cache, if it cache contain this then load from cache.
- Suppose first time we are giving, then cache dont have this information.
- So it tries to resolve the "google.com" string into an IP address,
- To conver IP address, firefox uses the DNS protocol,
- As mentioned above it will get the DNS IP address and request DNS for google IP address.
- Once it get the google.com IP address, then it will start the session to that IP address using TCP syn,
- Google will reply back with Ack+syn,
- Again firefox replay the ACK, now 3 way handshake is over and it will get the page from google and will load.
- Usually google.com doesn't give only one flow, many flows (connnection) will be used to load the single google page.
