You have typed market-web and reached a Service. Something turned that name into a cluster IP.

CoreDNS

Every Service gets a record:

CoreDNS serves these records. It is the Pod you found in kube-system in Chapter 2, behind the Service kube-dns.

What a Pod sees

Each Pod's /etc/resolv.conf points at CoreDNS and carries a search list:

search straits.svc.cluster.local svc.cluster.local cluster.local
nameserver 10.96.0.10

A short name is tried with each suffix in turn:

wget market-api
  1. market-api.straits.svc.cluster.local   ← same namespace: found
  2. market-api.svc.cluster.local
  3. market-api.cluster.local

So inside a namespace the bare Service name is enough.

Across namespaces

From namespace ops, market-api expands to market-api.ops.svc.cluster.local. No such record. Add the namespace:

Checking from a Pod

learner@shallows:~$ kubectl exec client -- nslookup market-api
Name:	market-api.straits.svc.cluster.local
Address: 10.96.191.79

nslookup prints the name it resolved and the cluster IP. NXDOMAIN means the name does not exist as searched.