There are several different types of black snakes with white rings.
I'll list those that I know of:
Death Adder
Stephen's Banded Snake
Bandy Bandy
California Mountain King Snake
Long Nosed Snake
I can't really think of anymore right now, but try typing these names into Google image search and see if you recognise any of these.
Depending on the order of the bands - either a highly-venomous Coral snake or a non-venomous milk snake.
If the red bands touch the yellow/white ones, then it is a coral snake. If the red bands touch the black ones it is a milk snake.
Milk snake and a milk snake has white bellies too
Probably a King snake. Hard to be more specific without more details.
Some more detailed info would have helped - however - it sounds like a banded king snake.
From your vague description - it sounds like you're describing a California King snake. See attached photo.
It is probably the Common Kingsnake (Lampropeltis getula).
A milk snake
its a Black & White Desert Phase California Kingsnake
The red-bellied black snake, which is native to eastern Australia, is black with a distinctive pink-red belly.
Diamondback rattlesnake
the Australian brown snake even tho it ain't brown prob a relative, also known as easten brown.
Sea Kraits are white with black stripes. Or black with white stripes if you like to look at it that way.They're a sea snake, highly venomous, but only aggressive when provoked repeatedly.King snakes are also black and white, striped. They are non-venomous, land based and eat other snakes.Hope this helped!
black snake
the worst kind
If the stripes are light in color, maybe even off white it could be a CA king snake.
It could be a juvenile so you wont be able to know. Do you know where it's native or where it was seen?
A ring-necked snake, a small snake that eats invertebrates such as slugs and worms.
Sounds like a killdeer.
coral snake