Example (last time it selected garr.it for me):
garr.it failed, and free.fr (few seconds later) succeeded.2013-05-26 19:17:04 4668 6 Status: Disconnected from server
2013-05-26 19:17:04 4668 6 Status: Downloading /updatecheck.php?platform=i586-pc-mingw32msvc&version=3.7.0.1&osversion=6.1&osarch=64
2013-05-26 19:17:04 4668 6 Status: Resolving address of update.filezilla-project.org
2013-05-26 19:17:04 4668 6 Status: Connecting to [2a01:4f8:160:7342::4]:443...
2013-05-26 19:17:04 4668 6 Status: Connection established, initializing TLS...
2013-05-26 19:17:05 4668 6 Trace: TLS Handshake successful
2013-05-26 19:17:05 4668 6 Trace: Protocol: TLS1.0, Key exchange: RSA, Cipher: AES-256-CBC, MAC: SHA1
2013-05-26 19:17:05 4668 6 Status: Verifying certificate...
2013-05-26 19:17:05 4668 6 Status: TLS/SSL connection established, sending HTTP request
2013-05-26 19:17:05 4668 6 Command: GET https://update.filezilla-project.org/updatecheck.php?platform=i586-pc-mingw32msvc&version=3.7.0.1&osversion=6.1&osarch=64 HTTP/1.1
2013-05-26 19:17:05 4668 6 Response: HTTP/1.1 200 OK
2013-05-26 19:17:05 4668 6 Response: Date: Sun, 26 May 2013 17:17:05 GMT
2013-05-26 19:17:05 4668 6 Response: Server: Apache
2013-05-26 19:17:05 4668 6 Response: Vary: Accept-Encoding
2013-05-26 19:17:05 4668 6 Response: Content-Length: 655
2013-05-26 19:17:05 4668 6 Response: Connection: close
2013-05-26 19:17:05 4668 6 Response: Content-Type: text/plain
2013-05-26 19:17:05 4668 6 Status: Disconnected from server
2013-05-26 19:17:05 4668 6 Status: File transfer successful, transferred 655 bytes in 1 second
2013-05-26 19:17:08 4668 6 Status: Disconnected from server
2013-05-26 19:17:08 4668 6 Status: Downloading /filezilla/FileZilla_3.7.0.2_win32-setup.exe
2013-05-26 19:17:08 4668 6 Status: Resolving address of downloads.sourceforge.net
2013-05-26 19:17:08 4668 6 Status: Connecting to 216.34.181.59:80...
2013-05-26 19:17:08 4668 6 Status: Connection established, sending HTTP request
2013-05-26 19:17:08 4668 6 Command: GET http://downloads.sourceforge.net/filezilla/FileZilla_3.7.0.2_win32-setup.exe HTTP/1.1
2013-05-26 19:17:09 4668 6 Response: HTTP/1.1 301 Moved Permanently
2013-05-26 19:17:09 4668 6 Response: Location: http://downloads.sourceforge.net/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe
2013-05-26 19:17:09 4668 6 Response: Content-type: text/html
2013-05-26 19:17:09 4668 6 Response: Content-Length: 0
2013-05-26 19:17:09 4668 6 Response: Connection: close
2013-05-26 19:17:09 4668 6 Response: Date: Sun, 26 May 2013 17:17:09 GMT
2013-05-26 19:17:09 4668 6 Response: Server: lighttpd/1.4.26
2013-05-26 19:17:09 4668 6 Status: Resolving address of downloads.sourceforge.net
2013-05-26 19:17:09 4668 6 Status: Connecting to 216.34.181.59:80...
2013-05-26 19:17:09 4668 6 Status: Connection established, sending HTTP request
2013-05-26 19:17:09 4668 6 Command: GET http://downloads.sourceforge.net/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe HTTP/1.1
2013-05-26 19:17:09 4668 6 Response: HTTP/1.1 302 Found
2013-05-26 19:17:09 4668 6 Response: Content-Disposition: attachment; filename="FileZilla_3.7.0.2_win32-setup.exe"
2013-05-26 19:17:09 4668 6 Response: Location: http://garr.dl.sourceforge.net/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe
2013-05-26 19:17:09 4668 6 Response: Set-cookie: sf_mirror_attempt=filezilla:garr:/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe; expires=Sun, 26-May-2013 17:19:09 GMT; Path=/
2013-05-26 19:17:09 4668 6 Response: Content-type: text/html
2013-05-26 19:17:09 4668 6 Response: Content-Length: 0
2013-05-26 19:17:09 4668 6 Response: Connection: close
2013-05-26 19:17:09 4668 6 Response: Date: Sun, 26 May 2013 17:17:09 GMT
2013-05-26 19:17:09 4668 6 Response: Server: lighttpd/1.4.26
2013-05-26 19:17:09 4668 6 Status: Resolving address of garr.dl.sourceforge.net
2013-05-26 19:17:10 4668 6 Status: Connecting to [2001:760:ffff:b0::34]:80...
2013-05-26 19:17:10 4668 6 Status: Connection established, sending HTTP request
2013-05-26 19:17:10 4668 6 Command: GET http://garr.dl.sourceforge.net/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe HTTP/1.1
2013-05-26 19:17:10 4668 6 Response: HTTP/1.1 302 Moved Temporarily
2013-05-26 19:17:10 4668 6 Response: Server: nginx/1.4.1
2013-05-26 19:17:10 4668 6 Response: Date: Sun, 26 May 2013 17:17:10 GMT
2013-05-26 19:17:10 4668 6 Response: Content-Type: text/html
2013-05-26 19:17:10 4668 6 Response: Content-Length: 160
2013-05-26 19:17:10 4668 6 Response: Connection: close
2013-05-26 19:17:10 4668 6 Response: Location: http://cdn.mirror.garr.it/sf/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe
2013-05-26 19:17:10 4668 6 Status: Resolving address of cdn.mirror.garr.it
2013-05-26 19:17:10 4668 6 Status: Connecting to [2001:760:ffff:b1::45]:80...
2013-05-26 19:17:10 4668 6 Status: Connection established, sending HTTP request
2013-05-26 19:17:10 4668 6 Command: GET http://cdn.mirror.garr.it/sf/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe HTTP/1.1
2013-05-26 19:17:10 4668 6 Response: HTTP/1.1 404 Not Found
2013-05-26 19:17:10 4668 6 Error: Disconnected from server
2013-05-26 19:17:10 4668 6 Error: File transfer failed
2013-05-26 19:17:23 4668 7 Status: Disconnected from server
2013-05-26 19:17:23 4668 7 Status: Downloading /updatecheck.php?platform=i586-pc-mingw32msvc&version=3.7.0.1&osversion=6.1&osarch=64
2013-05-26 19:17:23 4668 7 Status: Resolving address of update.filezilla-project.org
2013-05-26 19:17:23 4668 7 Status: Connecting to [2a01:4f8:160:7342::4]:443...
2013-05-26 19:17:23 4668 7 Status: Connection established, initializing TLS...
2013-05-26 19:17:23 4668 7 Trace: TLS Handshake successful
2013-05-26 19:17:23 4668 7 Trace: Protocol: TLS1.0, Key exchange: RSA, Cipher: AES-256-CBC, MAC: SHA1
2013-05-26 19:17:23 4668 7 Status: Verifying certificate...
2013-05-26 19:17:23 4668 7 Status: TLS/SSL connection established, sending HTTP request
2013-05-26 19:17:23 4668 7 Command: GET https://update.filezilla-project.org/updatecheck.php?platform=i586-pc-mingw32msvc&version=3.7.0.1&osversion=6.1&osarch=64 HTTP/1.1
2013-05-26 19:17:23 4668 7 Response: HTTP/1.1 200 OK
2013-05-26 19:17:23 4668 7 Response: Date: Sun, 26 May 2013 17:17:23 GMT
2013-05-26 19:17:23 4668 7 Response: Server: Apache
2013-05-26 19:17:23 4668 7 Response: Vary: Accept-Encoding
2013-05-26 19:17:23 4668 7 Response: Content-Length: 655
2013-05-26 19:17:23 4668 7 Response: Connection: close
2013-05-26 19:17:23 4668 7 Response: Content-Type: text/plain
2013-05-26 19:17:23 4668 7 Status: Disconnected from server
2013-05-26 19:17:23 4668 7 Status: File transfer successful, transferred 655 bytes in 1 second
2013-05-26 19:17:25 4668 7 Status: Disconnected from server
2013-05-26 19:17:25 4668 7 Status: Downloading /filezilla/FileZilla_3.7.0.2_win32-setup.exe
2013-05-26 19:17:25 4668 7 Status: Resolving address of downloads.sourceforge.net
2013-05-26 19:17:25 4668 7 Status: Connecting to 216.34.181.59:80...
2013-05-26 19:17:25 4668 7 Status: Connection established, sending HTTP request
2013-05-26 19:17:25 4668 7 Command: GET http://downloads.sourceforge.net/filezilla/FileZilla_3.7.0.2_win32-setup.exe HTTP/1.1
2013-05-26 19:17:26 4668 7 Response: HTTP/1.1 301 Moved Permanently
2013-05-26 19:17:26 4668 7 Response: Location: http://downloads.sourceforge.net/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe
2013-05-26 19:17:26 4668 7 Response: Content-type: text/html
2013-05-26 19:17:26 4668 7 Response: Content-Length: 0
2013-05-26 19:17:26 4668 7 Response: Connection: close
2013-05-26 19:17:26 4668 7 Response: Date: Sun, 26 May 2013 17:17:26 GMT
2013-05-26 19:17:26 4668 7 Response: Server: lighttpd/1.4.26
2013-05-26 19:17:26 4668 7 Status: Resolving address of downloads.sourceforge.net
2013-05-26 19:17:26 4668 7 Status: Connecting to 216.34.181.59:80...
2013-05-26 19:17:26 4668 7 Status: Connection established, sending HTTP request
2013-05-26 19:17:26 4668 7 Command: GET http://downloads.sourceforge.net/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe HTTP/1.1
2013-05-26 19:17:26 4668 7 Response: HTTP/1.1 302 Found
2013-05-26 19:17:26 4668 7 Response: Content-Disposition: attachment; filename="FileZilla_3.7.0.2_win32-setup.exe"
2013-05-26 19:17:26 4668 7 Response: Location: http://freefr.dl.sourceforge.net/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe
2013-05-26 19:17:26 4668 7 Response: Set-cookie: sf_mirror_attempt=filezilla:freefr:/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe; expires=Sun, 26-May-2013 17:19:26 GMT; Path=/
2013-05-26 19:17:26 4668 7 Response: Content-type: text/html
2013-05-26 19:17:26 4668 7 Response: Content-Length: 0
2013-05-26 19:17:26 4668 7 Response: Connection: close
2013-05-26 19:17:26 4668 7 Response: Date: Sun, 26 May 2013 17:17:26 GMT
2013-05-26 19:17:26 4668 7 Response: Server: lighttpd/1.4.26
2013-05-26 19:17:26 4668 7 Status: Resolving address of freefr.dl.sourceforge.net
2013-05-26 19:17:26 4668 7 Status: Connecting to [2001:1b48:10f::7]:80...
2013-05-26 19:17:26 4668 7 Status: Connection established, sending HTTP request
2013-05-26 19:17:26 4668 7 Command: GET http://freefr.dl.sourceforge.net/project/filezilla/FileZilla_Client/3.7.0.2/FileZilla_3.7.0.2_win32-setup.exe HTTP/1.1
2013-05-26 19:17:26 4668 7 Response: HTTP/1.1 200 OK
2013-05-26 19:17:26 4668 7 Response: Date: Sun, 26 May 2013 17:17:26 GMT
2013-05-26 19:17:26 4668 7 Response: Server: Apache/2.2.8 (FreeBSD)
2013-05-26 19:17:26 4668 7 Response: Last-Modified: Sun, 26 May 2013 16:25:03 GMT
2013-05-26 19:17:26 4668 7 Response: ETag: "aba6e18-496070-4dda1796555c0"
2013-05-26 19:17:26 4668 7 Response: Accept-Ranges: bytes
2013-05-26 19:17:26 4668 7 Response: Content-Length: 4808816
2013-05-26 19:17:26 4668 7 Response: Connection: close
2013-05-26 19:17:26 4668 7 Response: Content-Type: application/x-msdownload
2013-05-26 19:17:29 4668 7 Status: Disconnected from server
2013-05-26 19:17:29 4668 7 Status: File transfer successful, transferred 4,808,816 bytes in 3 seconds