How do I get rid of this message and in fact manage to update the machine?
A server with the specified hostname could not be found.
An error occurred while installing the selected updates.
I can browse internal and external websites fine, name resolution works fine, a packet capture
tcpdump -i en7 port 53 and subsequent analysis of the dump using tshark shows that the name software update requires resolves just fine:
1 0.000000 ww.xx.yy.zz → vv.ww.xx.yy DNS 76 Standard query 0xc474 A swscan.apple.com 2 0.014597 vv.ww.xx.yy → ww.xx.yy.zz DNS 210 Standard query response 0xc474 A swscan.apple.com CNAME swscan-cdn.apple.com.akadns.net CNAME swdist.apple.com.edgekey.net CNAME e5977.e9.akamaiedge.net A 22.214.171.124