What symbols are allowed in a domain name?

Related questions

1. Can a domain name contain numbers?
2. Do all email addresses have?
3. What does RFC 2544 stand for?
4. What's the difference between https and HTTP?
5. What is the .com called?
6. What are RFC standards?
7. What is the dash symbol in email?
8. Is hostname same as computer name?
9. Is http secure?
10. What are email etiquettes?

Tags

1. #answer
2. #names
3. #follow
4. #domain
5. #letters
6. #rules
7. #numbers
8. #spaces
9. #hyphens
10. #begin
11. #character
12. #allowed
13. #regardless
14. #extension
15. #dashes