About a third of these 55 interview questions are ones I thought of. The rest I picked from various postings around the web from people I think are worthy of attention. Credits are at the bottom.
Technical / Tactics
Every SEO prefers certain tactics over others, but familiarity with many could indicate a deeper understanding of the industry. And while every SEO doesn't need to have a web developer background, having such skills can help set someone apart from the crowd.
- Give me a description of your general SEO experience.
- Can you write HTML code by hand?
- Could you briefly explain the PageRank algorithm?
- How you created any SEO tools either from scratch or pieced together from others?
- What do you think of PageRank?
- What do you think of using XML sitemaps?
- What are your thoughts on the direction of Web 2.0 technologies with regards to SEO?
- What SEO tools do you regularly use?
- Under what circumstances would you look to exclude pages from search engines using robots.txt vs meta robots tag?
- What areas do you think are currently the most important in organically ranking a site?
- Do you have experience in copywriting and can you provide some writing samples?
- Have you ever had something you've written reach the front-page of Digg? Sphinn? Or be Stumbled?
- Explain to me what META tags matter in today's world.
- Explain various steps that you would take to optimize a website?
- If the company whose site you've been working for has decided to move all of its content to a new domain, what steps would you take?
- Rate from 1 to 10, tell me the most important "on page" elements
- Review the code of past clients/company websites where SEO was performed.
- What do you think about link buying?
- What is Latent Semantic Analysis (LSI Indexing)?
- What is Phrase Based Indexing and Retrieval and what roles does it play?
- What is the difference between SEO and SEM?
- What kind of strategies do you normally implement for back links?
- What role does social media play in an SEO strategy?
- What things wouldn't you to do increase rankings because the risk of penalty is too high?
- What's the difference between PageRank and Toolbar PageRank?
- Why might you want to use nofollow on an internal link?
Analysis
A big part of SEO involves assessing the effectiveness of a campaign both relative to past performance as well as to competing sites.
- Are you familiar with web analytics and what packages are your familiar with?
- From an analytics perspective, what is different between a user from organic search results vs. a type-in user?
- How do you distinguish the results of your search optimization work from a seasonal change in traffic patterns?
- How do you evaluate whether an SEO campaign is working?
- What does competitive analysis mean to you and what techniques do you use?
- If you've done 6 months of SEO for a site and yet there haven't been any improvements, how would you go about diagnosing the problem?
- How many target keywords should a site have?
- How do *you* help a customer decide how to their budget between organic SEO and pay-per-click SEM?
- You hear a rumor that Google is weighting the HTML LAYER tag very heavily in ranking the relevance of its results - how does this affect your work?
- Why does Google rank Wikipedia for so many topics?
Industry Involvement
Is SEO just a job to pay the bills? Nothing wrong with that, but some senior positions can benefit from more enthusiasm and interest that can be measured by work done outside of the office.
- If salary and location were not an issue, who would you work for?
- In Google Lore - what are 'Hilltop', 'Florida' and 'Big Daddy'?
- Have you attended any search related conferences?
- Google search on this candidates name, (if you cannot find them, that's a red flag).
- Do you currently do SEO on your own sites? Do you operate any blogs? Do you currently do any freelance work and do you plan on continuing it?
- Of the well-known SEOs, who are you not likely to pay attention to?
- What are some challenges facing the SEO industry?
- What industry sites, blogs, and forums do you regularly read?
- Who are the two key people - who started Google?
- Who is Matt Cutts?
- If you were bidding on a contract, what competitor would you most worry about?
Open-Ended
These questions are more about how an answer is given rather than the actual answer. They often scare interviewees, but with no wrong answer they're actually a good opportunity to shine.
- Tell me your biggest failure in an SEO project
- What areas of SEO do you most enjoy?
- In what areas of SEO are you strongest?
- In what areas of SEO are you weakest?
- How do you handle a client who does not implement your SEO recommendations?
- Can you get "xyz"? company listed for the keyword "Google"? in the first page?
- What do you think is different about working for an SEO agency vs. doing SEO in-house?
- Why are you moving from your current position and/or leaving any current projects?
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