The company I work for is planning on relaunching our website using a Global Load Balancing solution to ensure site visitors from around the world are directed to the geographically closest web server to ensure content loads as quickly as possible. The Global Load Balancing is achieved by customizing the DNS response sent back to the requester and providing only the IP address for the closest web server. If you access the site from different regions of the USA or around the world you will get 1 of 4 IP addresses. Our Marketing and SEO teams are concerned that if Google (and the other search engines) see the domain responding from more than a single IP address our rankings will suffer as each IP address will be viewed as a separate site - thus we would have 4 sites with duplicate content. Is this really a significant issue? Are there technical work arounds if this is an issue? What about using htaccess to test for the the useragent names and redirect all traffic from the bots to a specific IP address of one of the servers?
This isnt an issue, and load balancing is common on big websites; however; your company is doing it wrong. You cannot (realistically) customize the DNS due to propagation and caching. DNS is also round robin, meaning if you have multiple IP's YOU cannot control which one is returned at any given time. Your *front end* should be the load balancer which then processes the request through to the relevant server/cluster, thus negating what you are trying to achieve.