The web sites of drug store chain Rite Aid Corp. went off line for at least several hours today beginning at 2 p.m. Eastern, according to AlertBot, a web site monitoring service of InfoGenius Inc.

Efforts to contact the retailer’s headquarters in Camp Hill, PA, were unsuccessful, but a customer service rep said that both the retailer’s corporate site at RiteAid.com and its online store at Store.RiteAid.com were temporarily down. The rep didn’t provide a reason for the downtime.

Justin Noll, director of client experience at AlertBot, also did not give a specific reason for the site outage. But he says it could be attributed to one of three reasons:

routine maintenance, which was unlikely during the middle of the day;

a misconfigured domain name system record, which would prevent a web site’s URL or web site address from loading;

or downtime by the servers hosting the retailer’s DNS records, which would also prevent the retailer’s URL from loading.

Craig Oldham, vice president of digital engagement at The American Red Cross, will discuss web site performance in the session, “When consumers come, you gotta let ‘em in,” at the Internet Retailer Conference & Exhibition 2013 in June.