Yes the sample is right, one of the sub-domains in that domain is the parent and the other one is a child sub-domain. The reason i am saying the sample is correct is because in this instance the sample's domain infrastructure illustrates the domains tree structure for the domain's FQDN (Fully Qualified Domain Name). The sub-domains Accounting, www, Texas are resource records, Texas and Accounting is the A(host) record and www is the CNAME(alias) and also pointer records to reach an intended host or alias like: accounts.totalsem.com.
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Hope this makes sense.
If this does not make sense for you refer to this: Sub domain - Wikipedia, the free encyclopedia
"Everything is energy and that's all there is to it. Match the frequency of the reality you want and you cannot help but get that reality. It can be no other way. This is not philosophy. This is physics." Albert Einstein.
2019 Goals: [ICND1][ICDN2]-CCNA