You can switch your method of Domain Control validation from file-based to email-based for any SSL product that we provide. You can switch from email-based to file-based only for Comodo products.
UC stands for Unified Communications and is a newer type of SSL certificate that is designed and primarily used for securing Microsoft Exchange 2007 and Microsoft Office Communications Server 2007 products. The main difference between a UCC SSL and a standard Multi-Domain certificate is that a UCC can secure both internal network names and external domain names as well.
This largely depends on the type of Multi-Domain SSL certificate that you purchase. Comodo Multi-Domain certificates can cover up to 100 additional domains. Symantec and Thawte certificates can cover up to 25 additional domains. GeoTrust Multi-Domain certificates can cover anywhere between 25-100 additional domains, depending on the certificate.
That is the difference between the key lengths used once an SSL connection has been established in the browser. 256-bit security is indeed a bigger key however that does not necessarily mean it is more secure. Experts and research agrees that 128-bit is equally secure for the foreseeable future. The only reason 256-bit security is needed is if it’s specifically required by your industry or company policy. All our certificates have the ability to use either bit-length, which one you use is a matter of server configuration, NOT certificate support.