root@hp:~ # freebsd-update -r 11.0-RELEASE upgrade
Looking up update.FreeBSD.org mirrors... 4 mirrors found.
Fetching metadata signature for 11.0-RC2 from update3.freebsd.org... done.
Fetching metadata index... done.
Inspecting system... done.

The following components of FreeBSD seem to be installed:
kernel/generic src/src world/base world/doc world/lib32

The following components of FreeBSD do not seem to be installed:
kernel/generic-dbg world/base-dbg world/lib32-dbg

Does this look reasonable (y/n)? y

Fetching metadata signature for 11.0-RELEASE from update3.freebsd.org... failed.
Fetching metadata signature for 11.0-RELEASE from update6.freebsd.org... failed.
Fetching metadata signature for 11.0-RELEASE from update5.freebsd.org... failed.
Fetching metadata signature for 11.0-RELEASE from update4.freebsd.org... failed.
No mirrors remaining, giving up.