That table look's to be finished already. If it is there isn't a polyurethane intended to be slapped on over it. Have a piece of glass cut to fit over it.

What does the manufacturer say it was finished with? A dining table in this day and age should be poly to begin with.

Yes, it's finished. The manufacturer customer service said it is finished with a light lacquer. She said it would turn a white color if something hot was placed on it. Hotpads are grat but I guess I was thinking about spilled liquids if a glass was left on it. They suggested checking with a furniture store to see what they would recommend as far as additional coverage. I didn't really want to use a table cloth and thought additional polyurethane might help protect. Just a question from someone who doesn't know much about this and thought I'd ask here before going to the furniture or hardware store.

99% of new furniture is finished with some type of lacquer. Only if it was done in someone's garage by a DIY would it be poly.

Poly would not be a good coat for this. I had a job a number of years ago where the woman bought a new dining table and thought it should have a different sheen, so she "put on some poly." By the time I got there, nearly 1/4 of the top had peeled off. It was disaster to refinish. I had to sand off some of the poly to even get it to strip.

Most lacquers will "blush" when subjected to water, exacerbated by heat. It normally takes some effort to get this to happen. Just take care and I think you'll be OK.

You risk more damage by trying to prevent something by putting on poly than by just using it, IMO.