Do all spellcasters get interrupted?

Hi, I played only Paladin and Dragoon, now I am in Heavensward.

I played the Astrologist. How do I attack enemies? This is strange, I get interrupted when attacked? So how do I damage enemies?

When I attack enemy casters they keep casting, even when I cast interject most of the time 'interject had no effect'.

This is weird, do I have to stand at max range and kill them before they reach me?

Is this an Astrologist only thing?

In general you will only get interrupted when you take a lot of damage in a single hit. So if you were standing in an aoe that will interrupt your cast. Also moving of any sort will also interrupt your cast.

This is not limited to astrologian, this is for any and all casters in general as well as paladin when using their spells, as they have a cast time by default.

You get interrupted if you get hit for a certain percentage of your max HP in one hit. Surecast can prevent this but it most people don't make a habit of using Surecast in general play because it has mechanical importance in some fights and you need to save it for specific moments. You can survive one or two interrupted spells while you're killing something. Don't worry about it. If you need healing you have instant options.

Interject only works on actions that have a red cast bar with a pulsing outline.

Paladin does not get interrupted because of a trait, at least from level 64 and on. Blue mages get a stance that prevents cast interruptions.

You can prevent interruption on a caster by using Surecast, but in a duty someone should be tanking for you preventing interruption.

In the world you can use a chocobo companion and put points in the tank tree so that it tanks for you, preventing interruption.

It should not affect astrologian that much because the cast time is just 1.5 seconds. Black Mages have it worst with some cast times being 4 seconds, which are guaranteed to be interrupted without Manaward, Surecast or someone tanking for them.

Aha, that was very interesting to read.

Thank you this taught me a lot.

Think ahead is a good mantra for spellcasters.