Hai Kali Raj,
If you talk about in terms of development, the support projects are those application where client needs support for the enhancement of their products. In these types of application, they will have a big project which can be working since many years and will also use legacy technologies and old trends. But as the application could be huge, they can't migrate to the latest technologies as it takes lot of time and effort. So to keep those application working in the current environment, they need support for them. Support could be in terms of environment, could be OS level support etc.
So as a developer, we need to keep the application update and working with the current hardware an software support.
Also in these type of projects, the client slowly try to migrate the application in part so that the existing application should not disturb and they can easily update it with the supporting of old technologies.
Now in support there are few levels, depends on the company and project. It is not defined that there will be the L1, L2,L3 and L4. There could be many more or less levels.
L1 support is the type of support which need very less time to fix. Lets say some path got issue. Some network related problem. This is mostly handled at the client locations.
L2 support is the type of support where the L2 support team decides whether the issue should go to the below level or can they themselves fix as it also doesn't need any programming changes. Sometimes, the changes in the bindings(in BizTalk sever application), some configurations can come under this level.
The L3 support is probably comes to the development where there is the need of some code changes to fix the issue.
The L4 support might need more changes and will come to the junior level developers where there is the need to implement some new changes, ideas, enhancements etc.
Let me know if you need more details.
Hope it will be helpful to you.
Pawan Awasthi(DNS MVM)
+91 8123489140 (whatsApp), +60 14365 1476(Malaysia)