Why package installation with yum show wrong source repository?

Question

I have a brand new CentOS 7 VM. Right after a global yum -y update I'm trying to install additional packages, for instance net-snmp.

Package

net-snmp 1:5.7.2-33.el7_5.2 (updates)

Dependencies

1. lm_sensors-libs 3.4.0-4.20160601gitf9185e5.el7 (base)
2. net-snmp-agent-libs 1:5.7.2-33.el7_5.2 (updates)
3. net-snmp-libs 1:5.7.2-33.el7_5.2 (updates)
4. perl-Data-Dumper 2.145-3.el7 (base)

I don't understand why net-snmp, net-snmp-agent-libs and net-snmp-libs are referenced in "updates" repository, mainly because those ones do not appear in this repository: http://mirror.centos.org/centos/7/updates/x86_64/Packages/

Forcing "base" repository with yum install net-snmp --disablerepo=* --enablerepo=base shows a different version for net-snmp (which is logical) and all dependencies belong to the "base" repository:

Package

net-snmp 1:5.7.2-32.el7_5.2 (base)

Dependencies

1. lm_sensors-libs 3.4.0-4.20160601gitf9185e5.el7 (base)
2. net-snmp-agent-libs 1:5.7.2-32.el7_5.2 (base)
3. net-snmp-libs 1:5.7.2-32.el7_5.2 (base)
4. perl-Data-Dumper 2.145-3.el7 (base)

Why and how to fix this issue and make yum query the relevant repository to install net-snmp package and its dependencies?

Answer 1

The mirror link you posted is for CentOS 7.6.1810, but your current YUM repositories seem to be pointing to CentOS 7.5.1804. The current version of net-snmp from the CentOS 7.6 base repository would be 5.7.2-37.

Possible issues are your YUM repository configurations are pinned to a specific version of CentOS, or your configured repositories have not been updated to the current CentOS version yet. Cannot know for sure without seeing the contents of /etc/yum.repos.d/*.repo