SIDERA TO PROVIDE HIGH-CAPACITY CONNECTIVITY BETWEEN CORESITE DATA CENTERS

Sidera Connects Customers to CoreSite’s Robust Application and Cloud Services Ecosystems

Denver, CO and New York, NY – November 12, 2012 – CoreSite Realty Corporation (NYSE: COR), a national provider of powerful, network-rich data centers, and Sidera networks, the premier supplier of fiber optic-based network solutions, announced that Sidera is providing connectivity between CoreSite data centers located in critical communications markets including Chicago; Boston; New York; Washington, DC; and Reston, VA. Sidera’s high capacity network will support the requirements of CoreSite’s financial services, content delivery, web services, media and entertainment, and other high-bandwidth customers by providing the redundancy, diversity, and scalability required to effectively run performance-sensitive applications deployed in CoreSite’s data centers.

Sidera Networks is the leading provider of tailored, high-capacity communications services to both carrier and large enterprise customers. Sidera Networks offers a comprehensive suite of facilities-based services, including Ethernet, SONET, wavelength, dark fiber, and internet access.

Connecting through the Sidera network gives CoreSite customers immediate access to over 40 financial exchanges and the Sidera Xtreme Ultra-Low Latency Network, which was specifically designed for applications demanding the lowest latency and highest performance.

Additionally, as a result of the expansion into additional CoreSite data centers, Sidera will extend peering on CoreSite’s Any2 exchange, the nation’s second largest peering exchange. Sidera also will be able to provide seamless access to CoreSite’s Open Internet Exchange, an aggregation hub that gives expanded peering and interconnection opportunities to CoreSite customers.

“CoreSite has developed a successful model of attracting the largest content players, service providers, and end-customers and connecting them together at key exchange points around the country,” said Jarrett Appleby, COO, CoreSite. “This strategy relies on our selection of key fiber providers like Sidera to deliver high-performance networks for our customers’ applications.”

“Sidera is proud to be a part of CoreSite’s ecosystems,” said Clint Heiden, President, Sidera Networks. “Connecting multiple CoreSite facilities to our network ensures that our mutual customers will have diverse and scalable access to strategic data center resources, from carrier interconnection to cloud services to space, power, and storage.”

For further information on CoreSite, visit www.coresite.com or call 303-405-1000. Learn more about Sidera at www.sidera.net or call 877.669.6366.

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About CoreSite
CoreSite Realty Corporation (NYSE: COR) is a national provider of data center products and interconnection services. More than 750 customers such as Global 1000 enterprises, communications providers, cloud and content companies, financial firms, media and entertainment, healthcare, and government agencies choose CoreSite for the confidence that comes with customer-focused data center products, service and support systems, and scalability. CoreSite’s network-centric computing platform is a business catalyst, featuring the Any2 Internet exchange and network ecosystems, which include access to 225+ carriers and service providers and a growing mesh of more than 15,000 interconnections. The company features a diverse colocation offering from individual cabinets to custom cages and private suites, with 14 data center locations in nine major U.S. markets. For more information, visit www.CoreSite.com.

CoreSite Media Contact
Jeannie Zaemes | CoreSite Marketing Senior Director
+1 720.446.2006 | +1 866.777.CORE
Jeannie.Zaemes@CoreSite.com

About Sidera Networks
Sidera Networks, LLC www.sidera.net, is the premier provider of tailored, high capacity communications services to large enterprise, carrier, and data center customers with a focus on how customers connect to cloud services and access or distribute content. Sidera Networks offers a comprehensive suite of facilities-based services including: Ethernet, Wavelength, Dark Fiber, IP, SONET, Colocation and more. With a fiber optic network leveraging unique rights-of-way that delivers connectivity to the major metropolitan areas from Maine to Virginia and out to Chicago, as well as access to Toronto and London, Sidera is committed to delivering cost-effective, custom solutions coupled with superior industry expertise, service and support.

Sidera Media Contact
Joe Cumello | Sidera Marketing Vice President
+1 703.434.8275
Joe.Cumello@Sidera.com

Forward Looking Statements

This earnings release and accompanying supplemental information may contain forward-looking statements within the meaning of the federal securities laws. Forward-looking statements relate to expectations, beliefs, projections, future plans and strategies, anticipated events or trends and similar expressions concerning matters that are not historical facts. In some cases, you can identify forward-looking statements by the use of forward-looking terminology such as “believes,” “expects,” “may,” “will,” “should,” “seeks,” “approximately,” “intends,” “plans,” “pro forma,” “estimates” or “anticipates” or the negative of these words and phrases or similar words or phrases that are predictions of or indicate future events or trends and that do not relate solely to historical matters. Forward-looking statements involve known and unknown risks, uncertainties, assumptions and contingencies, many of which are beyond CoreSite’s control, that may cause actual results to differ significantly from those expressed in any forward-looking statement. These risks include, without limitation: the geographic concentration of CoreSite’s data centers in certain markets and any adverse developments in local economic conditions or the demand for data center space in these markets; fluctuations in interest rates and increased operating costs; difficulties in identifying properties to acquire and completing acquisitions; significant industry competition; CoreSite’s failure to obtain necessary outside financing; CoreSite’s failure to qualify or  maintain our status as a REIT; financial market fluctuations; changes in real estate and zoning laws and increases in real property tax rates; and other factors affecting the real estate industry generally. All forward-looking statements reflect CoreSite’s good faith beliefs, assumptions and expectations, but they are not guarantees of future performance. Furthermore, CoreSite disclaims any obligation to publicly update or revise any forward-looking statement to reflect changes in underlying assumptions or factors, of new information, data or methods, future events or other changes. For a further discussion of these and other factors that could cause CoreSite’s future results to differ materially from any forward-looking statements, see the section entitled “Risk Factors” in CoreSite’s most recent annual report on Form 10-K, and other risks described in documents subsequently filed by CoreSite from time to time with the Securities and Exchange Commission.