Is correspondence B.Tech a valid course? I think some companies do not allow this.

Yes, definitely distance education is valid for private jobs as well as government jobs. If a student wants to pursue a profession in the technical area, he must first obtain a B Tech degree. As distance education advances, every undergraduate and postgraduate degree is now offered in a distance or

As you know that a large number of engineers are graduating every year and that too by doing a regular full-time course, then also they face some difficulties getting placed, so please go for the full-time course.

The course is valid but it is true that some of the top companies don't consider it. So, it would be better to opt for the regular course.