Samsung SM-A305GT can be rooted using Odin tool.
Phone running on Binary 4 U4 can use this file.
How to check Binary in Samsung SM-A305GT?
To check Binary Turn the phone into recovery mode by holding Power + Volume UP.
It will display like this in recovery mode A305GTVJU4BTB3.
Here U4 represents Binary 4.
This process works only on Binary 4.
Tools & Software Required:
2- Odin tool
Steps to Root Samsung SM-A305GT using Odin tool:
1- Install Samsung usb driver.
2- Run odin tool and select Root File in PDA under Odin tool.
3- Connect phone in Download Mode. Press & Hold Power + Volume Up, Recovery mode will appear. Then using Volume Key, Select Reboot to Bootloader by pressing Power key.
4- Connect the phone to PC.
5- Flashing will start and the rooting will be done.