I'm not sure how to enable caching server... I'll do a search and see what I can come up with.
I ran a couple of swupd_syncd commands and got the following.
Mavericks-Server:~ macserver$ swupd_syncd -sync
Jan 6 15:01:26 Mavericks-Server.local swupd_syncd[6197] <Info>:
Jan 6 15:01:26 Mavericks-Server.local swupd_syncd[6197] <Info>: swupd_syncd 10.9 (155) for OS X Server 10.9 (Darwin/x86_64)
Jan 6 15:01:26 Mavericks-Server.local swupd_syncd[6197] <Info>: ========== Sync Started ==========
Jan 6 15:01:26 Mavericks-Server.local swupd_syncd[6197] <Info>: Checking service data location: /Library/Server/Software Update/Data/html
Jan 6 15:01:26 Mavericks-Server.local swupd_syncd[6197] <Info>: Retrieving catalog list
Jan 6 15:01:26 Mavericks-Server.local swupd_syncd[6197] <Error>: Metaindex file save failed (/Library/Server/Software Update/Data/html/catalogs.sucatalog.alternate)
Jan 6 15:01:26 Mavericks-Server.local swupd_syncd[6197] <Error>: Public (exported) metaindex file save failed (/Library/Server/Software Update/Data/html/catalogs.sucatalog)
Jan 6 15:01:26 Mavericks-Server.local swupd_syncd[6197] <Info>: Retrieving deprecated udpates list
Jan 6 15:01:27 Mavericks-Server.local swupd_syncd[6197] <Error>: Download for "Deprecations.plist" failed (reason: The operation couldn’t be completed. (NSURLErrorDomain error -3001.))
Jan 6 15:01:27 Mavericks-Server.local swupd_syncd[6197] <Info>: Retrieving remote catalog (SECURE): index-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog
Jan 6 15:01:28 Mavericks-Server.local swupd_syncd[6197] <Warning>: Download for "index-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog.download" failed (reason: The operation couldn’t be completed. (NSURLErrorDomain error -3001.))
Jan 6 15:01:28 Mavericks-Server.local swupd_syncd[6197] <Info>: Retrieving remote catalog (STANDARD): index-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog
Jan 6 15:01:30 Mavericks-Server.local swupd_syncd[6197] <Warning>: Download for "index-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog.download" failed (reason: The operation couldn’t be completed. (NSURLErrorDomain error -3001.))
Jan 6 15:01:30 Mavericks-Server.local swupd_syncd[6197] <Error>: All download attempts failed for catalog index-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog
Jan 6 15:01:30 Mavericks-Server.local swupd_syncd[6197] <Info>: Retrieving remote catalog (SECURE): index-lion-snowleopard-leopard.merged-1.sucatalog
Jan 6 15:01:31 Mavericks-Server.local swupd_syncd[6197] <Warning>: Download for "index-lion-snowleopard-leopard.merged-1.sucatalog.download" failed (reason: The operation couldn’t be completed. (NSURLErrorDomain error -3001.))
Jan 6 15:01:31 Mavericks-Server.local swupd_syncd[6197] <Info>: Retrieving remote catalog (STANDARD): index-lion-snowleopard-leopard.merged-1.sucatalog
Jan 6 15:01:35 Mavericks-Server.local swupd_syncd[6197] <Warning>: Download for "index-lion-snowleopard-leopard.merged-1.sucatalog.download" failed (reason: The operation couldn’t be completed. (NSURLErrorDomain error -3001.))
Jan 6 15:01:35 Mavericks-Server.local swupd_syncd[6197] <Error>: All download attempts failed for catalog index-lion-snowleopard-leopard.merged-1.sucatalog
Jan 6 15:01:35 Mavericks-Server.local swupd_syncd[6197] <Info>: Retrieving remote catalog (SECURE): index-leopard-snowleopard.merged-1.sucatalog
Jan 6 15:01:36 Mavericks-Server.local swupd_syncd[6197] <Warning>: Download for "index-leopard-snowleopard.merged-1.sucatalog.download" failed (reason: The operation couldn’t be completed. (NSURLErrorDomain error -3001.))
Jan 6 15:01:36 Mavericks-Server.local swupd_syncd[6197] <Info>: Retrieving remote catalog (STANDARD): index-leopard-snowleopard.merged-1.sucatalog
Jan 6 15:01:40 Mavericks-Server.local swupd_syncd[6197] <Warning>: Download for "index-leopard-snowleopard.merged-1.sucatalog.download" failed (reason: The operation couldn’t be completed. (NSURLErrorDomain error -3001.))
Jan 6 15:01:40 Mavericks-Server.local swupd_syncd[6197] <Error>: All download attempts failed for catalog index-leopard-snowleopard.merged-1.sucatalog
Jan 6 15:01:40 Mavericks-Server.local swupd_syncd[6197] <Error>: Unable to retrieve one or more of the catalogs listed in the index
Jan 6 15:01:40 Mavericks-Server.local swupd_syncd[6197] <Error>: Unable to retrieve catalog(s) from the Apple server
Jan 6 15:01:40 Mavericks-Server.local swupd_syncd[6197] <Info>: Sync Complete
Mavericks-Server:~ macserver$ swupd_syncd -showDeprecated
Jan 6 15:02:31 Mavericks-Server.local swupd_syncd[6243] <Info>: Checking service data location: /Library/Server/Software Update/Data/html
Jan 6 15:02:31 Mavericks-Server.local swupd_syncd[6243] <Info>: Retrieving catalog list
Jan 6 15:02:31 Mavericks-Server.local swupd_syncd[6243] <Error>: Public (exported) metaindex file save failed (/Library/Server/Software Update/Data/html/catalogs.sucatalog)
Jan 6 15:02:31 Mavericks-Server.local swupd_syncd[6243] <Info>: Retrieving deprecated udpates list