Why does yum update fail with public key not installed during install or disconnected RHN Satellite 5.3 installation ?

Issue

• Why does RHN packages install fail, with "Public key for " during disconnected RHN Satellite 5.3 installation ?

      Transaction Summary
      ================================================================================
      Install    260 Package(s)         
      Update       0 Package(s)         
      Remove       0 Package(s)         
      Total size: 1.2 G
      Total download size: 53 M
      Downloading Packages:
      --------------------------------------------------------------------------------
      Total                                           2.1 GB/s |  53 MB     00:00     
      warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID 37017186
  
      Public key for perl-NOCpulse-Gritch-1.27.4-1.el5sat.noarch.rpm is not installed
  

• Why does yum update fails with message "Public key for <package> is not installed" ?

  $ yum update
  ...
  Install      22 Package(s) 
  Upgrade       7 Package(s) 
  Total size: 42 M 
  Is this ok [y/N]: y 
  Downloading Packages: 
  attention: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID 37017186 
  rhel-x86_64-server-5/gpgkey                              | 1.1 kB     00:00      
  Public key for device-mapper-multipath-0.4.7-34.el5.x86_64.rpm is not installed