Sudo commands take long to run (more than 10 seconds)

Issue

sudo commands take more than 10 seconds to run. These messages are found in /var/log/secure:

Sep 17 15:34:00 rhel-host sudo[213372]:    root : TTY=pts/4 ; PWD=/home/admin ; USER=root ; COMMAND=/bin/id
Sep 17 15:34:05 rhel-host sudo[213372]: pam_radius_auth: RADIUS server 192.168.1.10 failed to respond
Sep 17 15:34:05 rhel-host sudo[213372]: pam_radius_auth: All RADIUS servers failed to respond.
Sep 17 15:34:05 rhel-host sudo[213372]: pam_unix(sudo:session): session opened for user root by admin(uid=0)
Sep 17 15:34:10 rhel-host sudo[213372]: pam_radius_auth: RADIUS server 192.168.1.10 failed to respond
Sep 17 15:34:10 rhel-host sudo[213372]: pam_radius_auth: All RADIUS servers failed to respond.
Sep 17 15:34:10 rhel-host sudo[213372]: pam_unix(sudo:session): session closed for user root