Does every domain name have ip address. When we ping the domain name it gives the ip address(is that ip address of server or domain name).
When you ping or trace a domain name it goes to the IP of the server that the domain is hosted on. It's not unusual for several domain names to have the same IP (this is sometimes referred to as named based hosting)
Afraid it is more complicated than that - the relationship is actually many-to-many in both directions. A domain (or hostname to be precise) can have multiple IPs and multiple hostnames can resolve to the same IP.
Yes every domain must have ip address but doesn't mean each domain have unique ip address though. The ip address is from where you host the domain.
You can put a lot of domains on 1 IP address, you don't need to have a separate IP for each of your domains. Sites with SSL certificates should be put on a unique IP though.
Every computer connected to the network has unique IP address but one machine can host many domain .. Something called Virtual Hosting ( if i am correct ).