To the shame and embarrassment of their authors, web browsers and proxy HTTP servers still do not perform SRV lookups. Web browser software authors have still, 6 years after the idea was first proposed, to add SRV lookup to their web browsers.
*The work item for having SRV lookups added to Mozilla has languished for over 5 years.
*Squid doesn't yet employ SRV lookups.
*Whilst Microsoft Windows Server networking is an exemplar that many point to when discussing the use of SRV resource records, whilst Microsoft's Windows 2000 Resource Kit even gives examples of _http._tcp SRV resource records, and whilst the suggestion having been on Microsoft's suggestions list for a couple of years now, Microsoft's own Internet Explorer still does not perform SRV lookups.